Time for an update. I cannot get my FP2 to turn on at all.
I have, however, following this guide, disassembled my core module.
Using a multimeter, I found that I likely have a short to ground somewhere.
Since I fortunately have access to a thermal camera, I looked around where that short might be. And I did find a likely culprit.
Right next to the RAM/CPU stack is a large SMD component. If you look at the images in that guide, it’s the large one right above the pink heatspreader in the 8th image. This is very likely a capacitor. Mine measures as having practically no resistance, and when applying power to the battery terminals, it gets hot.
I’ve sent a support request to Fairphone, hoping that they will tell me what value the replacement should have.
Is there someone who has also stripped down their core module, and could check this component for resistance? That would help me verify that my guess is correct.