Let me know if need any more info.
If you read the CPU or battery's temperature (any app) it will show 2 to 3 times the real temperature. On my case, it should be reading around 25 ºC (I had a similar working Pixel nearby) while it was showing around 60 ºC. The main problem with this is that the phone will be throttling all the time while perfectly cold. I did not measure any CPU performance, but the battery wouldn't charge more than 10-20 mA per hour while switched off.
I guess that while disconnecting the battery I forced a resistor which is (AFAIK) related to the CPU & battery temperature measuring circuit. I had a faulty main board around so I could compare them. Fortunately I found a missing resistor and I could measure it on the faulty MB. The part you will need is a 1.00 kΩ 1% 0201 inch (0603 metic) thik film resistor. I've use a Vishay CRCW02011K00FKTDBC.
Just solder another one.
I'm not going to give you much soldering details as I think this out of scope and you'll notice right away if you feel you can do it once you look how tiny these resistor are.
- very small tweezers:
- very small 0.2mm soldering tip:
- head mounted magnifying
Here is, red highlighted, the resistor that was missing and now soldered. It's on top of battery's socket: