Thank you very much for this guide! The browser-based installer from e/OS/ did not work and with your guide I came a lot further.
Nevertheless… I fear I bricked my new Fairphone 5, after the successful installation of e/OS/, while trying to re-lock the bootloader: ./fastboot flashing lock_critical worked as described, but after the ./fastboot flashing lock the device said it’s unsafe and only boots to the bootloader and nowhere else. Here is a log of my fastboot commands on Windows:
fastboot commands on Windows
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot devices
<SERIAL> fastboot
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot oem device-info
(bootloader) Verity mode: true
(bootloader) Device unlocked: true
(bootloader) Device critical unlocked: true
(bootloader) Charger screen enabled: true
OKAY [ 0.001s]
Finished. Total time: 0.006s
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing get_unlock_ability
(bootloader) get_unlock_ability: 1
OKAY [ 0.000s]
Finished. Total time: 0.000s
me@myPC MINGW64 /c/adb/platform-tools
$ cd _fp5
me@myPC MINGW64 /c/adb/platform-tools/_fp5
$ ls -la
total 4719109
drwxr-xr-x 1 <USERNAME> 197121 0 Mar 10 12:07 ./
drwxr-xr-x 1 <USERNAME> 197121 0 Mar 10 12:07 ../
-rw-r--r-- 1 <USERNAME> 197121 155648 Feb 11 18:05 abl.img
-rw-r--r-- 1 <USERNAME> 197121 208804 Feb 11 18:05 aop.img
drwxr-xr-x 1 <USERNAME> 197121 0 Feb 11 18:05 bin-darwin/
drwxr-xr-x 1 <USERNAME> 197121 0 Feb 11 18:05 bin-linux-x86/
drwxr-xr-x 1 <USERNAME> 197121 0 Feb 11 18:05 bin-msys/
-rw-r--r-- 1 <USERNAME> 197121 3518464 Feb 11 18:05 bluetooth.img
-rw-r--r-- 1 <USERNAME> 197121 100663296 Feb 11 18:05 boot.img
-rw-r--r-- 1 <USERNAME> 197121 186628 Feb 11 18:05 cpucp.img
-rw-r--r-- 1 <USERNAME> 197121 54200 Feb 11 18:05 devcfg.img
-rw-r--r-- 1 <USERNAME> 197121 67108864 Feb 11 18:05 dsp.img
-rw-r--r-- 1 <USERNAME> 197121 25165824 Feb 11 18:05 dtbo.img
-rwxr-xr-x 1 <USERNAME> 197121 9475 Feb 11 18:05 factory.common*
-rw-r--r-- 1 <USERNAME> 197121 86480 Feb 11 18:05 featenabler.img
-rwxr-xr-x 1 <USERNAME> 197121 500 Feb 11 18:05 flash_FP5_factory.sh*
-rw-r--r-- 1 <USERNAME> 197121 3699872 Feb 11 18:05 hyp.img
-rw-r--r-- 1 <USERNAME> 197121 65536 Feb 11 18:05 imagefv.img
-rw-r--r-- 1 <USERNAME> 197121 271789 Feb 11 18:05 keymaster.img
-rw-r--r-- 1 <USERNAME> 197121 190541824 Feb 11 18:05 modem.img
-rw-r--r-- 1 <USERNAME> 197121 13400 Feb 11 18:05 multiimgoem.img
-rw-r--r-- 1 <USERNAME> 197121 57269 Feb 11 18:05 qupfw.img
-rw-r--r-- 1 <USERNAME> 197121 45616 Feb 11 18:05 shrm.img
-rw-r--r-- 1 <USERNAME> 197121 245760 Feb 11 18:05 studybk.img
-rw-r--r-- 1 <USERNAME> 197121 4331714164 Feb 11 18:05 super.img
-rw-r--r-- 1 <USERNAME> 197121 3777848 Feb 11 18:05 tz.img
-rw-r--r-- 1 <USERNAME> 197121 125201 Feb 11 18:05 uefisecapp.img
-rw-r--r-- 1 <USERNAME> 197121 8192 Feb 11 18:05 vbmeta.img
-rw-r--r-- 1 <USERNAME> 197121 4096 Feb 11 18:05 vbmeta_system.img
-rw-r--r-- 1 <USERNAME> 197121 100663296 Feb 11 18:05 vendor_boot.img
-rw-r--r-- 1 <USERNAME> 197121 3688576 Feb 11 18:05 xbl.img
-rw-r--r-- 1 <USERNAME> 197121 225496 Feb 11 18:05 xbl_config.img
me@myPC MINGW64 /c/adb/platform-tools/_fp5
$ ./flash_FP5_factory.sh
INFO: You are using MinGW on Windows.
INFO: Looking for connected device(s)...
INFO: One Fairphone 5 in fastboot mode found (serial number: <SERIAL>).
Info: Your phone is in regular bootloader mode.
Sending 'bluetooth_a' (3436 KB) OKAY [ 0.079s]
Writing 'bluetooth_a' OKAY [ 0.000s]
Finished. Total time: 0.095s
Sending 'bluetooth_b' (3436 KB) OKAY [ 0.079s]
Writing 'bluetooth_b' OKAY [ 0.047s]
Finished. Total time: 0.126s
Sending 'devcfg_a' (52 KB) OKAY [ 0.000s]
Writing 'devcfg_a' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'devcfg_b' (52 KB) OKAY [ 0.000s]
Writing 'devcfg_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'dsp_a' (65536 KB) OKAY [ 1.592s]
Writing 'dsp_a' OKAY [ 0.173s]
Finished. Total time: 1.765s
Sending 'dsp_b' (65536 KB) OKAY [ 1.593s]
Writing 'dsp_b' OKAY [ 0.094s]
Finished. Total time: 1.687s
Sending 'modem_a' (186076 KB) OKAY [ 4.549s]
Writing 'modem_a' OKAY [ 0.614s]
Finished. Total time: 5.163s
Sending 'modem_b' (186076 KB) OKAY [ 4.550s]
Writing 'modem_b' OKAY [ 0.630s]
Finished. Total time: 5.180s
Sending 'xbl_a' (3602 KB) OKAY [ 0.086s]
Writing 'xbl_a' OKAY [ 0.016s]
Finished. Total time: 0.111s
Sending 'xbl_b' (3602 KB) OKAY [ 0.095s]
Writing 'xbl_b' OKAY [ 0.015s]
Finished. Total time: 0.110s
Sending 'tz_a' (3689 KB) OKAY [ 0.094s]
Writing 'tz_a' OKAY [ 0.015s]
Finished. Total time: 0.110s
Sending 'tz_b' (3689 KB) OKAY [ 0.094s]
Writing 'tz_b' OKAY [ 0.016s]
Finished. Total time: 0.110s
Sending 'hyp_a' (3613 KB) OKAY [ 0.095s]
Writing 'hyp_a' OKAY [ 0.032s]
Finished. Total time: 0.126s
Sending 'hyp_b' (3613 KB) OKAY [ 0.094s]
Writing 'hyp_b' OKAY [ 0.032s]
Finished. Total time: 0.126s
Sending 'keymaster_a' (265 KB) OKAY [ 0.000s]
Writing 'keymaster_a' OKAY [ 0.000s]
Finished. Total time: 0.016s
Sending 'keymaster_b' (265 KB) OKAY [ 0.017s]
Writing 'keymaster_b' OKAY [ 0.000s]
Finished. Total time: 0.017s
Sending 'abl_a' (152 KB) OKAY [ 0.016s]
Writing 'abl_a' OKAY [ 0.000s]
Finished. Total time: 0.016s
Sending 'abl_b' (152 KB) OKAY [ 0.000s]
Writing 'abl_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'aop_a' (203 KB) OKAY [ 0.016s]
Writing 'aop_a' OKAY [ 0.000s]
Finished. Total time: 0.016s
Sending 'aop_b' (203 KB) OKAY [ 0.000s]
Writing 'aop_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'featenabler_a' (84 KB) OKAY [ 0.000s]
Writing 'featenabler_a' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'featenabler_b' (84 KB) OKAY [ 0.000s]
Writing 'featenabler_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'imagefv_a' (64 KB) OKAY [ 0.000s]
Writing 'imagefv_a' OKAY [ 0.012s]
Finished. Total time: 0.016s
Sending 'imagefv_b' (64 KB) OKAY [ 0.000s]
Writing 'imagefv_b' OKAY [ 0.000s]
Finished. Total time: 0.016s
Sending 'multiimgoem_a' (13 KB) OKAY [ 0.000s]
Writing 'multiimgoem_a' OKAY [ 0.000s]
Finished. Total time: 0.000s
Sending 'multiimgoem_b' (13 KB) OKAY [ 0.000s]
Writing 'multiimgoem_b' OKAY [ 0.000s]
Finished. Total time: 0.000s
Sending 'qupfw_a' (55 KB) OKAY [ 0.000s]
Writing 'qupfw_a' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'qupfw_b' (55 KB) OKAY [ 0.000s]
Writing 'qupfw_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'uefisecapp_a' (122 KB) OKAY [ 0.016s]
Writing 'uefisecapp_a' OKAY [ 0.003s]
Finished. Total time: 0.018s
Sending 'uefisecapp_b' (122 KB) OKAY [ 0.000s]
Writing 'uefisecapp_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'xbl_config_a' (220 KB) OKAY [ 0.016s]
Writing 'xbl_config_a' OKAY [ 0.000s]
Finished. Total time: 0.016s
Sending 'xbl_config_b' (220 KB) OKAY [ 0.016s]
Writing 'xbl_config_b' OKAY [ 0.000s]
Finished. Total time: 0.016s
Sending 'cpucp_a' (182 KB) OKAY [ 0.016s]
Writing 'cpucp_a' OKAY [ 0.000s]
Finished. Total time: 0.016s
Sending 'cpucp_b' (182 KB) OKAY [ 0.000s]
Writing 'cpucp_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'shrm_a' (44 KB) OKAY [ 0.000s]
Writing 'shrm_a' OKAY [ 0.000s]
Finished. Total time: 0.000s
Sending 'shrm_b' (44 KB) OKAY [ 0.000s]
Writing 'shrm_b' OKAY [ 0.016s]
Finished. Total time: 0.016s
Sending 'boot_a' (98304 KB) OKAY [ 2.394s]
Writing 'boot_a' OKAY [ 0.236s]
Finished. Total time: 2.630s
Sending 'boot_b' (98304 KB) OKAY [ 2.393s]
Writing 'boot_b' OKAY [ 0.377s]
Finished. Total time: 2.770s
Sending 'dtbo_a' (24576 KB) OKAY [ 0.597s]
Writing 'dtbo_a' OKAY [ 0.068s]
Finished. Total time: 0.665s
Sending 'dtbo_b' (24576 KB) OKAY [ 0.601s]
Writing 'dtbo_b' OKAY [ 0.081s]
Finished. Total time: 0.682s
Sending 'vendor_boot_a' (98304 KB) OKAY [ 2.352s]
Writing 'vendor_boot_a' OKAY [ 0.260s]
Finished. Total time: 2.612s
Sending 'vendor_boot_b' (98304 KB) OKAY [ 2.327s]
Writing 'vendor_boot_b' OKAY [ 0.236s]
Finished. Total time: 2.562s
Sending 'vbmeta_a' (8 KB) OKAY [ 0.000s]
Writing 'vbmeta_a' OKAY [ 0.000s]
Finished. Total time: 0.000s
Sending 'vbmeta_b' (8 KB) OKAY [ 0.000s]
Writing 'vbmeta_b' OKAY [ 0.000s]
Finished. Total time: 0.000s
Sending 'vbmeta_system_a' (4 KB) OKAY [ 0.000s]
Writing 'vbmeta_system_a' OKAY [ 0.000s]
Finished. Total time: 0.000s
Sending 'vbmeta_system_b' (4 KB) OKAY [ 0.000s]
Writing 'vbmeta_system_b' OKAY [ 0.012s]
Finished. Total time: 0.012s
Sending sparse 'super' 1/6 (758485 KB) OKAY [ 18.683s]
Writing 'super' OKAY [ 0.000s]
Sending sparse 'super' 2/6 (784869 KB) OKAY [ 19.445s]
Writing 'super' OKAY [ 0.016s]
Sending sparse 'super' 3/6 (785925 KB) OKAY [ 19.485s]
Writing 'super' OKAY [ 0.000s]
Sending sparse 'super' 4/6 (726947 KB) OKAY [ 17.664s]
Writing 'super' OKAY [ 0.000s]
Sending sparse 'super' 5/6 (786236 KB) OKAY [ 19.525s]
Writing 'super' OKAY [ 0.016s]
Sending sparse 'super' 6/6 (387724 KB) OKAY [ 9.555s]
Writing 'super' OKAY [ 0.000s]
Finished. Total time: 104.467s
******** Did you mean to fastboot format this f2fs partition?
Erasing 'userdata' OKAY [ 3.295s]
Finished. Total time: 4.176s
******** Did you mean to fastboot format this ext4 partition?
Erasing 'metadata' OKAY [ 0.000s]
Finished. Total time: 0.000s
Setting current slot to 'a' OKAY [ 0.031s]
Finished. Total time: 0.031s
-----------
INFO: Done. The device will reboot now.
Rebooting OKAY [ 0.000s]
Finished. Total time: 0.000s
INFO: You can unplug the USB cable now.
me@myPC MINGW64 /c/adb/platform-tools/_fp5
$ cd ..
me@myPC MINGW64 /c/adb/platform-tools
$ ./adb devices
* daemon not running; starting now at tcp:5037
* daemon started successfully
List of devices attached
<SERIAL> unauthorized
me@myPC MINGW64 /c/adb/platform-tools
$ ./adb devices
List of devices attached
<SERIAL> device
me@myPC MINGW64 /c/adb/platform-tools
$ ./adb reboot bootloader
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot oem device-info
(bootloader) Verity mode: true
(bootloader) Device unlocked: true
(bootloader) Device critical unlocked: true
(bootloader) Charger screen enabled: true
OKAY [ 0.001s]
Finished. Total time: 0.001s
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing get_unlock_ability
(bootloader) get_unlock_ability: 1
OKAY [ 0.000s]
Finished. Total time: 0.000s
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing lock_critical
OKAY [ 0.027s]
Finished. Total time: 0.027s
<HERE THE DEVICE REBOOTED AND I ENABLED USB DEBUGGING AGAIN>
me@myPC MINGW64 /c/adb/platform-tools
$ ./adb devices
List of devices attached
<SERIAL> device
me@myPC MINGW64 /c/adb/platform-tools
$ ./adb reboot bootloader
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot oem device-info
(bootloader) Verity mode: true
(bootloader) Device unlocked: true
(bootloader) Device critical unlocked: false
(bootloader) Charger screen enabled: true
OKAY [ 0.001s]
Finished. Total time: 0.001s
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing get_unlock_ability
FAILED (Write to device failed (Unknown error))
fastboot: error: Command failed
<IT SEEMS I OVERLOOKED THAT ERROR, SIGH>
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing lock
OKAY [ 0.026s]
Finished. Total time: 0.026s
<HERE THE DEVICE REBOOTED, SAID IT WAS UNSAFE, AND SINCE THEN IT ONLY REBOOTS TO BOOTLOADER>
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot oem device_info
FAILED (remote: 'unknown command')
fastboot: error: Command failed
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing get_unlock_ability
(bootloader) get_unlock_ability: 1
OKAY [ 0.000s]
Finished. Total time: 0.000s
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing lock
FAILED (remote: ' Device already : locked!')
fastboot: error: Command failed
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot reboot
Rebooting OKAY [ 0.000s]
Finished. Total time: 0.000s
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot flashing get_unlock_ability
(bootloader) get_unlock_ability: 1
OKAY [ 0.000s]
Finished. Total time: 0.000s
me@myPC MINGW64 /c/adb/platform-tools
$ ./fastboot oem device-info
(bootloader) Verity mode: true
(bootloader) Device unlocked: false
(bootloader) Device critical unlocked: false
(bootloader) Charger screen enabled: true
OKAY [ 0.001s]
Finished. Total time: 0.001s
me@myPC MINGW64 /c/adb/platform-tools
$
The Android version was 15 and the Android security patch was February 5, 2026 for the original Android when I did the unlocking. The e/OS/ (“IMG-e-3.5-a15-20260211580868-official-FP5.zip”) also is Android 15 and from a later date in February (11th according to file name).
Update: By simply using ./fastboot flashing unlock and ./fastboot flashing unlock_critical as recommended by this guide I was able to unlock and unbrick my device and install e/OS/ again.
Please note that this post shall in no way critize your guide - I just want to find out what I did wrong. And whether there is any way to un-brick my device.