Charging paused. Battery temperature too low.

I originally had a power button problem, but fixed it by removing the old power button and soldering in a new one. Now the power button works! But the phone no longer charges. Every time I plug it in, I get the error message "Charging paused. Battery temperature too low."

I don't think it's the charging port because a) it worked fine before the power button replacement and b) I bypassed the charging port by connecting USB wires to the little open ports in the back of the phone like this guy demonstrates (https://www.youtube.com/watch?v=mwTrlMom...) and trying to charge the phone that way - same problem.

I don't think it's the battery because I used two other batteries and encountered the same problem.

In addition the phone can't access the camera, so I think that part of the board is fried somewhere, possibly one of the itty bitty resistors, or maybe a short somewhere. Or maybe the thermistor, but I don't know where the thermistor is, what it looks like, or how to check if any of the resistors are blown.

I'm getting a new motherboard, which is the logical solution, but it would have been fun and interesting to be able to fix this.

Thanks!