Random reboot loops and battery issues

Help Fairphone 4
1

Hello,

on Friday and then today my FP4 has had massive issues to the point of being almost unusable.

What happens is that it starts rebooting many times in a row. This has taken the following forms so far:

  1. start booting and show the Android logo, start booting again.
  2. boot up to SIM pin entry, then show a “Shutting down” popup with a loading circle
  3. boot up to SIM Pin entry. After entering the SIM pin, wait a few seconds, then it reboots

When it starts going into a reboot loop it just keeps going forever apparently until I remove the battery or force-kill it. After waiting a bit, it sometimes seems to fix itself.

While in this reboot loop, the display is also acting up: it keeps going completely dark for a split second every once in a while (despite not turning off), sometimes the screen shows weird artifacts like green line patterns.

Sometimes after successfully rebooting, the battery display shows a certain percentage and then ticks down one percent every couple seconds. After losing about 10% of battery in 1 - 2 mins it stabilizes.

I once had it on the charger right after getting out of a boot loop, but it was actually not really charging (it gained 7% over the course of an hour) and when I unplugged the charger it still showed “fast charging” while losing 10% in a matter of seconds (same as decribed above).

Do any of you know why this might be happening? Is this just the battery needing replacement? But I find the behavior very strange and some of it sounds more like a software issue (e.g. the fact that it can show a “shutting down” screen sometimes)

Some additional details:

  • the phone is 3 years old and I haven’t replaced any parts yet
  • a battery-health app I have says the battery is at 83% capacity
  • I’m on Android 15

After upgrading to Android 15 I also had the random reboots issue described here: FP4 bootloop after Android 15 update (SREL 15.14.4) — Android 13 factory boots fine - #4 by yvmuell
though this stopped happening after I switched my mobile provider about 10 days ago. It was also only about twice a day, not running into bootloops where it repeats for 10 times in a row or similar.

2

I would probably try to have my phone plugged in and monitor the output of the adb log during the loop process. It would show what is happening and possibly the why as well.

3

I have the exact same issue with A15 on FP4. I tried taking out the battery and cleaning the connectors, forced shutdown and reboot, keeping it in the charger and also this seemlingly weird fix, where you start the camera app immediately after boot. Together it seems to work, but I’m unsure exactly which thing does the trick.

Until this point it’s still annoyingly an ongoing issue.

4

Hello, I have exactly the same issue with my FP4. Did you find any solution ?

5

I’ have not.

It’s also getting worse, with my phone basically unable to boot now when it is not on the charger (though it can live without the charger as long as I don’t use it much)

I’ve ordered a new battery, but since I don’t live in Europe, it will take a while and I won’t be able to report back if that fixed it until in about 4 weeks.