Fair phone crashes just like that

But in that case most likely the problem was caused by a loose connection. Since the FP1 doesn’t have the modular design I doubt it could be the same issue. The bloated battery problem on the other hand is a well known issue with FP1.
But it is too bad that they already out again of spare batteries (and displays).

@ber
If you’re a bit tech savvy, you could try this: