This also happened to me after I activated “QuickBoot”. Endless reboots and the only thing appearing for less than a second was the app optimization. Strangely, the phone was reachable via “adb shell” while doing this loop and I could even use su there, get logfiles etc.
I suspected that the installation of privileged F-Droid (which I had tried but failed before the last reboot) was failing: https://f-droid.org/forums/topic/installed-as-privileged-now-phone-stuck-at-boot-logo/ but also deleting the folder in “priv-apps” did not help.
I don’t know enough about Android to find the exact problem and also waiting did not help but the phone got quite warm (there are many messages about temperatures in the logs 
) So I now did a hard reset via recovery. Fun fact: user data is gone, but things like su and silencing the camera survive it 
If someone is curious about this, I can provide the “adb logcat” output via pm or email.
Fun fact: user data is gone, but things like su and silencing the camera survive it
That’s good to know, though not very surprising: my understanding of factory reset is that it only wipes or cleans the /data partition.
Which also means: For any mess we make in the /system partition, a factory reset won’t help 
Same thing happened to me – and unfortunately the “wait and sleep” strategy didn’t work for me.
Setup:
- Encryption enabled
- Quickboot enabled
- two SIM cards and a microSDXC card inserted
- German language
- FP2 not rooted or flashed
What I did:
- Switched on my FP2 (well, obviously not really, due to Quickboot).
- Removed the battery
- Exchanged one SIM card (for a new one that is not yet activated before Monday).
- Inserted the battery again
- Switched on my FP2 again
What happened first:
- I was asked for my encryption key.
- On top of this, I was asked (in the foreground) for my first SIM card’s PIN and afterwards for my second SIM card’s PIN.
- After providing both SIM card PINs I was able to provide the encryption key.
What happened then (in a loop):
- The blue “Fairphone” banner and afterwards the white “Fairphone / Start a movement” banner appeared.
- The white screen with the blinking text “Loading…” appeared.
- The text stopped to blink.
- A “popup” on background appeared, stating “App X of Y is optimized” (“App X von Y wird optimiert”)
- (Goto 1)
I noticed that the numbers X and Y both changed. At least I saw X being 7 and 15 and Y being 175 and 202. I assume that 202 is the total number of installed apps, whereas 175 is the total number of enabled apps (as I disabled most Google apps).
I tried:
- wiping the cache partition (in Recovery Mode)
- removing the SIM cards / microSDXC card
- the “wait and sleep” strategy (for 6 hours)
But the problem persisted. As I’m going on vacation today (which makes this even more annoying), I won’t be able to share further insights before Tuesday, but I won’t give up trying (because a hard reset currently isn’t an option for me).
By the way, is there any way to backup the /data partition before the hard reset (note: device not rooted)?
Hi @clsbln, do you have developer options and USB debugging enabled? Then you can still try “adb shell” and poke around to get your data. And if you need root to access what you want, in principle you can still root now - I also flashed the boot loader while my FP2 had the reboot problem. This will give you “su” in the adb shell.
Since today, my FP2 cannot boot anymore.
It seems a bit like this issue with FP1: Fairphone does not boot anymore
When I switch the phone on, I first get the black screen with the Fairphone and Android logo, then the blue screen with the Fairphone logo, then the light grey one with the “loading…” text.
After a few minutes, I get a message box for a very short time (cannot read it or take a photo). Then the procedure starts again with the blue screen and the light grey one.
I can only stop this by removing the battery.
During this the phone gets quite wam (CPU is running…).
I have fast boot mode enabled.
Same behaviour with 2 SIMs, 1 SIM, no SIM and no SD card.
Maybe related: In the recent days I experienced some (2-3) sudden reboots during a telephone call.
Hi Jakob!
Hm that doesn’t sound good. Have you tried to dis- and reassemble the battery? Otherwise, I only have the following ideas:
Disclaimer: Only try the following, if you don’t mind losing all your data. Otherwise, my only suggestion would be to contact support (scroll down to the bottom of the site).
Do you have a backup of your data? If so or if you don’t mind loosing the data, you could try a hard reset, i.e. wipe data/factory and cache in the recovery menu (see step 2 in these instructions). Just to be sure, I mention it again: All your data will be lost after this!
If this doesn’t work, there is also a topic about a soft bricked FP2 (your phone is not “bricked” but at least also screwed up). The solution there is to flash a fresh copy (a zip file) of the OS via recovery, which will also erase all your data! However, I’m not familiar with the procedure there and can’t estimate how complicated this is.
Btw what do you mean by that? If you power on your phone with the power button, then the phone is in the mode of booting the OS. In this mode, there is no possibility for fastboot to be enabled. Fastboot mode is accessed after turning off the phone by pressing and holding the Volume Down and the power button for a few seconds. Note: in this mode you’ll only see a Fairphone logo and nothing else will happen.
Yes I disassembled the battery several times because this was the only way to interrupt the loading/boot mechanism.
I did not know about how to use the fastboot mode. I have always used the power button.
I will try the “wait & sleep” strategy.
In fastboot mode, the phone itself does nothing. This mode is only good for controlling the phone from the PC (via USB connection), for example to flash images or format partitions.
Hey guys, I also was forced to chose the harsh alternative: hard reset (admittedly I wasn’t patient enough for sleep’n’wait option). However, strangely it did not occur after first time booting with quickboot. After I set it on quickboot, I tried it - and it just worked perfectly! But then the other morning it did not start again, symptoms as you’ve described. I am curios how that could be resolved, the quickboot is still kinda appealing to me although it made me set up the thingy all over again 
I think we need to differentiate between Fastboot and Quickboot as I believe it brought some confusion into this threat.
Fastboot, as @tphysm described, is an interface to use with your pc, most often used to make serious changes to the operating system or replacing it completely.
Quickboot is a feature that can be enabled in the settings of the FP2 that will shorten the boot sequence, since it doesn’t switch off the phone completely but rather sets it to standby. This is for now the only way to make an alarm work, while the phone is switched off, apparently because the timers etc. are still running…
Good news: I was able to solve the problem by giving my FP2 more time (> 24 h) to escape the boot loop (right after wiping the cache partition once more, to be sure).
To me it seems like
- Android has to “optimise” each app after the phone has not been powered off properly,
- the order in which the apps are optimised is random and
- the process crashes after each app optimisation.
Then it would take as much time as it requires for each app to be randomly chosen to be the first app to be optimised.
And to clarify: The QuickBoot mode we’re talking about can be enabled only once the Android developer options have been activated. The developer menu then contains the item “Enable QuickBoot mode” which is described as follows: Put device into QuickBoot mode instead of normal power off.
In theory, I could imagine that this problem does not only affect phones with enabled QuickBoot mode but more generally any FP2 that hasn’t been powered off properly.
Hi clsbn,
I took my FP2 off the charger after being in “the death loop” for around 24h.
My question: How can i wipe the cache partition?
@Moritz: Thanks for clarification. Yes, I was talking about the Quickboot feature.
Power off the phone. Go to recovery mode by holding Volume Up and power button at the same time for a few seconds till the phone vibrates. Wait for android image and then for the menu. Navigate down by using Volume buttons to “wipe cache partition” and confirm with the power button. Then you can reboot the system (first entry in the recovrey).
I now reset my phone after nothing else worked… 
Waiting worked for me too! It took around 4 hours of constant reboots, until it worked again! Thanks for suggesting to wait!
I also tried to activate quickboot.
After 4 hours of endless reboot, i looked closer what happening.
With a camera and rewind, it is possible to read clearly the status between each reboot :
Optimizing app…
4/145
20/192
19/192
17/192
15/192
15/192
4/146
16/192
17/192
13/192
15/192
16/192
…
11/192
20/192
…not very encouraging and a bit weird.
Finally, I did not want to let my FP2 rebooting all night and let it overheating (after more than four hours, it was already very hot).
So I did a hard reset (which erases all data) to recover my phone.
My advice : DON’T try to activate currently the quickbook !
For Fairphone devs, i have the logcat of the last bootloop. Ask me on PM if you want a copy.
Kept mine on the charger, on and off for 2 days, then on the third day it rebooted, got rid of any boot boosters, and have had no more trouble !!!
JUST BE PATIENT
However keep it mind that, normaly it, shouldnt take more than 15 minutes.
Definitly, there is an unwanted bug and we cannot advice to enable quickboot in this conditions.
Furthermore, I’m not sure that’s a good thing for such device to run at 100% CPU for a such a long duration (48h of endless reboot?!).
I do not know if it’s the patience or the pleasure of making risky experiment.
@keesj did you take a look at this issue?
@alexisju we did spend some time on understanding what is going on there but did not yet manage to capture a log (logcat) for further analysis.
What I did was leave it on, charging, in the same room as me during the day after someone on the forum suggested 24 hr reboot to cure a loop. I notice the interval between boots was getting shorter each time I turned it of at .night. On the 4th day I had decided to get rid of it but tried one last time. After about half an hour too my amazement it started and went through the boot. I quickly stopped any boot boosting, including All in one toolbox which came up during the boot. Since then it has got better and is running ok ???!! All I need now is a sim socket repair kit and it will be ok !!.