A week after an accident with water, my fairphone 4 has started bootlooping. After extensive drying it would work normally at first, but start bootlooping after some time. After doing this a few time it is now constantly bootlooping. The problem seems to be coming from the power button, which is always pressed.
By dissassembling part of the phone, i can separate the button contacts from the mainboard and avoid this behaviour. Touching the two bottom contact on the mainboard triggers power button behaviour, so i think the mainboard is mostly fine. But using a multimeter on the two bottom contacts on the frame read ~3kΩ instead of Open Loop like the volume buttons contacts (pressing reads ~1Ω for all of them). I concluded that there must be a short Somewhere in the frame, constently triggering the power button signals.
Unfortunately extensive drying, scrubbing and flushing with isopropyl alcohol hasn’t helped. I can’t see anything that would explain this, and i’m not sure i understand the delayed appearance of this problem. I have used a piece of paper on the bottom contact to prevent contact between the frame and the mainboard to use the phone mostly normally, and noticed that the fingerprint reader is also not working.
Does anyone has any idea how to fix this? Sending it to the repair center for such a simple component seems overkill (and pricey) so i would like to try a few thing myself before that.
Hey, just solved this one on my phone. Exact same symptoms :
first fix : unscrewing the photo module a little, and adding a little bit of paper over the battery to prevent the cover from pressing it in. Alleviated the short, but not always.
changing the frame : the problem is the power button or the frame. The rest works fine. Unfortunately, the frame goes with a mainboard, and that’s the part you can’t get readily. You can by a non-functionning FP4 to harvest the part
what I just did : tape the power button contacts on the frame. You can use the power button anymore, so to boot, you have to pop the battery out, then back in, plug in a charger, and unplug as soon as the Fairphone logo appears. Should not happen too often, but yeah. For the regular unlock, the fingerprint reader still works fine for me. I’ve no great solution for locking the screen yet, but there are loads of apps that do that, such as when double taping the status bar.
Since this morning, my FP4 (on latest update) is also stuck in a bootloop, after a few seconds of the new green-yellow FAIRPHONE logo, it reboots automatically. Seems to be very reminiscent of what is described by the two of you above!
I tried all of the above: there was some corrosion on the power button contacts which I cleaned. Only after cleaning did I test the resistance with a multimeter, which seems to be correct (infinite resistance across the two contacts when the Power button is not pressed, resistance quickly drops to nearly zero (to 1 ohm) when the Power button is pressed).
However after putting it back together (already tried a few times), it still enters the bootloop! It does not seem like the power button is stuck or shorted, since also I CAN enter the bootloader, and from there it does not automatically activate one of the options. I can use the up/down buttons at my leasure and hang in that menu as much as I want. However selecting power off, or boot into recovery mode, or restart all result in the same bootloop again.
I also tried taping off the two contacts as you suggest, which did not work for me, still had the bootloop.
