System died again! Had replaced logic board what did I miss?

Hello,

I recently replaced thermal paste on my 2008 MacBook Pro 15” A1286 and after doing so the motherboard went bad, I’m guessing I applied to much paste that it damaged the CPU and GPU, after about a month of the system sitting I bought a new motherboard and installed it,

The MacBook Pro still wouldn’t boot until I went back through and found that the keyboard connector was loose and wasn’t pushed all the way in.

After fixing the cable it proceeded to turn on, but on start-up the fans were maxed out at 6000 RPM and the system wasn’t reading the temperature of the CPU and the fans were not detected by MacFanControl app, After performing a SMC System Manager reset it fixed the issue, the system booted up fine, all sensors were reading correctly and the fans were identified in MacFanControl.

But after 10 minutes of surfing in Safari the system powered down by itself and doesn’t turn on. I tried a SMC again but nothing happens.

The motherboard that is currently installed is brand new logic board from iFixit and the system worked perfectly and was reading the fans and temperature after the first SMC reset but now it doesn’t turn on.

After reading forum after forum I still can’t find a solution. so here I am hoping someone may have a solution to my problem.

Thanks in advance!