Chosen Solution
I bought this phone broken, the upper part of the aluminum frame was bent a lot. So I basically bent it back to its place, swapped front camera, sensor and the upper loudspeaker. Now I am noticing that the phone sometimes gets stuck in boot loop of sorts, and if i press the spot where CPU is, it boots up normally. Usually it works for 10-30 minutes or so, and then reboots, and starts the cycle again. So I’m thinking it’s the CPU’s fault, how can I sort this issue? I am only a hobbyist, don’t know anything about soldering, but since the phone cost me 40€, I am willing to give it a try with something I am not experienced in.
The CPU is underfilled, meaning that it is secured in place with a form of epoxy. That limits the options somewhat as you can’t just do an oven reflow because the expanding solder balls have nowhere to go and typically bridge adjacent balls or blow out from underneath the IC. The ideal solution is a reball but that is also fraught with danger as removing the CPU can damage the pads underneath. So theoretically, this is probably fixable but in practice there are no guarantees it will work.
