Gateway laptop will not turn on

Hello,

Ok so here's the problem I got my dad's gateway NV52 to come on and work by removing the battery and unplugging it then I plugged it back in and pushed the power button and Fn F6 was super happy but it was running hot so I took it apart and cleaned it and replaced the thermal paste on the CPU and GPU now when I try to turn it back on I get the blue led to come on but nothing else I tried the Fn F6 and that don't work I tried unplugging it and holding down the power button for 60 seconds that don't work and I can't figure it out please help