PS4 ultra-rapid overheat on broken console after repair

Right now i have a PS4 that i managed to get from dead to booting. A year ago it suddenly shutdown due to overheat to never come back on. Today i got it all disassembled, deep cleaned and brand new heat pads and thermal paste applied. Right now the PS4 manage to boot and idle in the menu’ for 15 mins before going in overheat shutdown. The top metal plating of the motherboard doesn’t get that hot while it runs apart from the zone near the back ports. I suspect a power supply fault but it seems to be working fine (+12v +5v rails are fine), also a visual inspection of the power supply internals didn’t suggest any damage. It can’t be the motherboard otherwise it wouldn’t boot i suppose, also the fan look fine (it spins freely and i’ve seen it moving when turned on). any tips?
Also, if anyone knows where all the PS4 thermistor are it would be a info of great value for my troubleshooting.