[SOLVED] HP Omen underperforming even after applying new thermal paste. Help

[soumyakantarma]

Hello !! I have a 2 years old HP Omen. 16GB RAM, GTX 1060 and Intel i7 8th Gen.
A few ago the laptop's battery puffed up so I had to take it out. Since that time my laptop's gaming performance has deteriorated.
Games that used to run at ore than 80 fps in normal/high settings are now running at 20-30 fps at low settings.
I thought it might be due to thermal paste, so i applied a new one. Now the games run smoothly for 5 mins and then the performance goes bad.

What could be the reason?
Please help

 

[Vic 40]

Might be switching to igp to safe energy, so from gtx 1060 to HD 630, is only thing i can think off.