Although it's hard to determine from the photo, the most likely cause of the issue is mild damage to the PCB at the charger connector. This is not uncommon, because the continual insertion and removal of the cable connector flexes the PCB trace and solder joint. Look also for any tiny break in the trace on the other side of the PCB. You observation that the ...
I have replaced the CPU thermal paste and drilled holes around the bottom of the laptop casing to allow air to get in. I also got a laptop cooler stand. I upgraded the RAM too
I ran two CPU tests in the bios. I get around:
I have not used the laptop cooling stand much. There was not much difference with the cooling fan stand on ...