Trapped in fastboot mode with locked bootloader and corrupted custom ROM

First contacted support on June 14, I received a new phone on June 27 free of charge because the phone was 2 days old.

Lesson learned. Don’t play to much with the bootloader :smiley:


So, here is my experience with cordon and FP support:
First contact June 05, received phone at Jun 29.
It could be faster if I sent it earlier.
Free of charge, however Cordon sent me the phone with different back-lid. I had a green one with speckles. Now it’s just plain green. Also, I had a something similar to popit for extra grip. That’s weird. I hope to get the original back cover.

Hello everyone,

I read a lot of stuff in the forum about this and some seems to be lucky (get_ability=1) after installing CalyxOs or Iodé for example, but others don’t.

Does anybody have any new information about this from the Fairphone dev team? What could we do to accelerate their response and/or get their attention (all of us creating a ticket)?

I would clearly want to flash a custom rom with relockable bootloader but as this is my main phone, I will avoid this process until they have fixed this bootloader issue (that seems to be open since a long time now).

Have a nice evening :slight_smile:

They are aware and working on a solution.


And will be open for another long time, my opinion.

Take the risk and do it.

I flashed my FP4, via my detailed instructions, now several times (iode, LeOS, FPOS, back to iode each time) and I was always able to lock it again without bricking.
It is important to do all steps very exactly! And nothing else!

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@yvmuell Ok thanks

So an other question, let’s say I take the risk and that the “get_unlock_ability=0”, would it be possible via a simple firmware update to solve this? If not, the phone would be unlocked forever :frowning:

Ok so for your IodéOS =>

" If you get 1, everything is fine.

Then start again, beginning at Step 8)

1. remove SIM card and check that akku has at least 50%
2. eneable USB Debugging and “Allow unlock OEM” in Developer Options
3. check if adb is working and device is recognized correctly =>adb devices => ACK USB debugging on phone-screen. check box: always trust
4. adb reboot bootloader
5. check if fastboot is working and device is recognized correctly =>fastboot devices
6. fastboot flashing unlock => Acknowledge unlocking on phone (VOLUME UP + POWER) Device is doing a factory reset and reboots to system
7. start again in bootloader => switch phone off. pull out USB cable. press Volume (-) and put in USB cable in. Keep Volume (-) pressed. Phone should start in bootloader. (¹)
8. check if fastboot is working and device is recognized correctly =>fastboot devices
9. fastboot flash recovery_a iode-3.0-20220530-FP4-recovery.img
10. fastboot flash recovery_b iode-3.0-20220530-FP4-recovery.img
11. fastboot erase avb_custom_key
12. fastboot flash avb_custom_key avb_custom_key-FP4.bin
13. press VOLUME UP until see message reboot in recovery. Then POWER
14. From recovery => Factory reset => Format Data/factory reset
15. From recovery => Apply update => Apply from ADB =>adb sideload
16. back to bootloader mode. From recovery => Advanced => reboot to bootloader
17. check if bootloader unlock ability is possible =>fastboot flashing get_unlock_ability → (bootloader) get_unlock_ability: 1 ==> if you get 1 then follow with step 18) otherwise do not lock bootloader (can brick your phone) and follow with step 19)
18. fastboot flashing lock
19. reboot system. First should see a Lineage screen doing a wipe. After a second (automatic) boot you should see the yellow boot screen and then the iode bootscreen.
20. start setup wizard

(¹) From FP Support Page:
Alternatively, you can disconnect the USB cable, turn off your Fairphone, then connect the cable and hold the volume down button. After a few seconds, you’ll see the fastboot mode"

ps: for your instructions back to stockOS, did you use the procedure given by fairphone?

if get get 0 you have a problem and a bricked phone.
if you get zero before locking bootloader again, never try to lock ist!

actual guide:

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At least if the phone doesn’t boot. :crazy_face:

That’s imho the important rule to follow if you want to be safe.


Same problem here after trying to install Iodé.

Contacted support on June 23rd, I sent another message yesterday (June 29th) and got a reply today (June 30th) telling me that it can be repaired by shipping to France repair center for around 30 € (not under manufacturing warranty because problem happened after trying to install a third-party OS).

They told me the same thing, but the repair price ended up being 0€ anyway.

How go back to Fairphone stock Os from calyxos or E/OS without bricking the phone?

Well I’m glad I followed my intuition and chose not to lock the bootloader when installing CalyxOS, given all the headaches people have had with returning to FPOS afterwards.

For the record, when I installed CalyxOS and skipped the last instruction (fastboot flashing lock), I got a strange behaviour where I was being dumped in the recovery after a couple bootloops, stating that my files were corrupt and I had to perform a factory reset. It was a bit of a scare, but after performing the factory reset I booted into Calyx and all seems to be working really well (it’s been a week).

By the way, could someone explain why in the instructions from CalyxOS it offers two steps to unlock the bootloader, and whether both are necessary? These are the steps:

  1. fastboot flashing unlock_critical
  2. fastboot flashing unlock

In my case, I went ahead by executing both commands in the shell, but it felt redundant, especially given that for the OnePlus 8T they mentioned only the second step (fastboot flashing unlock).

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Welcome to the community :wave:

I’m glad to hear you didn’t end up as another victim of a bricked FP4 :tada:

fastboot flashing unlock_critical unlocks the critical partitions so they can be overwritten through fastboot commands, fastboot flashing unlock unlocks the bootloader which makes all of this possible in the first place.

For a list of critical partitions see:


Thank you @hirnsushi , I’m really glad to be here!! Coming from a Huawei where the manufacturer would not even provide codes to unlock the bootloader, this is such a thrilling experience to have a manufacturer that not only permits tweaks but also works with the community of users and developers to provide as much official guidance and support as possible (even if Fairphones devs seem to have been slow to react/resolve these issues around the manual installation of FPOS through fastboot).

While were at it, do you think there is a chance of encountering this problem if one tries to flash FPOS with an unlocked bootloader as opposed to a locked one? Because in that case, perhaps the fix would just be to make sure the bootloader is unlocked on your custom rom before you revert back to stock android?

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You need an unlocked bootloader to flash anything to your phone stock FPOS or custom ROM doesn’t make a difference. The biggest :triangular_flag_on_post: is if get_unlock_ability=0 after flashing a ROM, if that happens definitely don’t lock the bootloader!

It’s been confirmed that the Fairphone devs are still working on a fix for whatever causes phones to brick, but as you mentioned there hasn’t been a update to the factory images in quite some time.
Maybe Fairphone are using Valve Time internally? :man_shrugging: :smirk:


Oh of course, silly me. The last phone I had I kept with the bootloader unlocked, so I never tried to see whether you could flash a factory image through fastboot with a locked bootloader on a custom rom.

Ahaha, yes indeed, it seems they are on a different temporal wavelength for this one!

Jetzt hat es mich auch erwischt. :cry:
Keine Chance im locked Bootloader das FP4 wieder zum laufen zu bringen. Das FP4 lief bis vor paar Tagen tadellos mit /e/OS. Mein Mädchen kam dann auf die Idee das mit der Google-Version alles “bequemer” ist. :man_facepalming: Hatte mit meinem alten FP4 (128GB) ja auch paar Probleme wegen den Slots, das konnte ich aber beheben.
Jetzt geht garnichts mehr.
Und die Warnung bezüglich “corrupt” hatte ich auch nicht.
Hat von euch schon jemand eine Idee oder Lösung ohne das Telefon zu FP einzuschicken?


Now it’s got me too. :cry:
No chance to get the FP4 running again in the locked bootloader. The FP4 was running fine with /e/OS until a few days ago. My girl then came up with the idea that with the Google version everything is “more comfortable”. :man_facepalming: I had some problems with my old FP4 (128GB) because of the slots, but I could fix that.
Now nothing works.
And the warning regarding “corrupt” I also did not have.
Does anyone of you have an idea or solution without sending the phone to FP?

Wenn Du das unlock-Kommando vom bootloader nicht akzeptiert wird, dann ist höchstwahrscheinlich OEM unlock deaktiviert (ist meiner Erfahrung nach auch der Standard, wenn du von /e/OS auf FPOS wechselst). Dann habe ich bisher von keiner Alternative zum Einsenden gehört. Da jetzt ja aber FPOS installiert ist (und nur nicht mehr hochfährt) stehen vermutlich die Chancen relativ gut, dass es auf Garantie läuft…

EDIT: hattest du den bootloader direkt nach der Installation wieder gesperrt - oder erst nach dem Hochfahren und Prüfen, ob es eine noch neuere Update-Version gibt? Es hält sich weiter das (vielleicht wahre) “Gerücht”, dass das Problem dann auftreten kann, wenn du von einem neueren Patchlevel auf einen älteren wechselst…

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Hallo Volker.
Die Installation (Stock-Rom) war fertig und ich wollte den Bootloader wegen der Warnmeldung sperren und dann die neuen Updates über die Einstellungen installieren.
Dazu kam es aber garnicht erst. Ganz “normal” über die Console gelockt und auf dem FP4 bestätigt. Dann war Feierabend und nur noch der Fastboot Modus und Locked.
Das Gerät wird über fastboot devices erkannt, aber alle Eingaben enden mit not allowed bzw not in locked mode :cry: