OEM unlock + fastboot unlock + fastboot critical unlock = boot loop?


A friend of mine has bought a FairPhone4 and asked me to install /e/OS on it.

I was too quick and I started unlocking phone to prepare /e/OS installation. Then I realized that latest Android security update of FairPhoneOS is from April 5th 2022, whereas /e/OS are from March 5th 2022.

So I did not install /e/OS, I only unlocked the phone.

Here are all the steps I followed:

  • use OEM unlock page and unlock OEM in developer options → error
  • update to latest FairPhoneOS and unlock OEM (in dev. options) → ok
  • adb reboot bootloader → ok
  • fastboot flashing unlock & approve → ok
  • fastboot flashing unlock_critical & approve → ok

I did nothing more on the phone.
At this time I double checked /e/OS version to use and viewing all these forum posts about FP4 stuck and android security updates, I decided to stop here.

Strange thing is that FairPhoneOS doesn’t boot anymore ?!? :scream:
After some booting loops, following screen appears (screenshot of FP4 taken with another FP4 device :wink: ):

Should I go on and make factory reset ?
Was it predictable that “simple” unlock and critical unlock lead to bootloop ?
Should I open an issue ? If yes, with what kind of info inside ?

Low Memory, too quick to unlock; too slow to double check android security updates

I’d recommend the factory reset. IMHO it can’t get worse as it only cleans the data partition (which btw should also be done by the unlocking steps, but well…).


Unlocking the phone will force the phone to do a factory reset after reboot. Same goes for re-locking.

I guess you interrupted the “normal” procedure that normally triggers this factory reset, and now the phone is confused. Wipe the data and you should be good to go.


A quick update here:

after factory reset, I could reboot phone without problems !

Thanks for all and Regards !


FYI, I installed /e/ just recently, and noticing that the original firmware had a security update newer than the /e/ rom I was installing, I did not lock the bootloader yet. Everything works normally, just the bootloader is still unlocked.

Waiting for an updated /e/ and then I will lock it again (well, also I need to find a reasonably working camera app, otherwise I may go for de-googling the original rom instead).

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Just to confirm: I have installed /e/OS 0.23-r-20220413178020 successfully.

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Just to share experience: I installed /e/OS 1.0 on FP4 and I could successfully fastboot lock_critical and fastboot lock.

All set for my friend to go! :slight_smile:

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