Help! Laptop turning off immediately on running games with Nvidia.

I just got my laptop repaired and thermals reinstalled because the fan was not working and it was shutting down due to overheating after using it or playing games for some minutes.

Now the fan is working properly and it doesn't seem to be getting that hot.
But even if I run old less demanding games using Nvidia GPU, the laptop is turned off even before getting into the main menu after the intro. Though I am able to start the game with Integrated Intel graphics (not playable).

I tried reinstalling the Nvidia drivers as well. Please help. It has never happened before.

(Dell Inspiron n5110, Nvidia GT525M)