Question Laptop won't startup after removing and returning heat sink

[Nifemi10]

I was having issues with my lenovo y40-80fa i7 5500u laptop,with CPU clocking down and up within 10mins of playing games, interrupting badly with the laptops performance, so in my opinion , I thought the laptop in a way is trying not to fry the processor,so i opened it up to check maybe it's well ventilated and dust free,which it is,fan working well etc.

Then I asked myself what's the issue let me check the processor and GPU thermal paste,I removed the heat sink(Think I applied little pressure while doing that) and the thermal paste was like half liquid half plastic,looks weird then I returned the heat sink(I don't have thermal paste) closed the laptop and boom it won't come up,no black screen but it won't turn on and the crazy thing is that when I tried charging the laptop it charges and I can still charge my phone from the USB(it has always on USB for charging) pls help have I fried my processor or GPU or motherboard PS I was seeing something about grounding yourself when working with motherboards which don't think I did

 

[rgd1101]

redo the thermal paste. next time don't remove heat sink if you don't redo the thermal paste

 

[Nifemi10]

redo the thermal paste. next time don't remove heat sink if you don't redo the thermal paste

Thanks for your reply,but how do I go about that,I haven't done it before and I do not know the best type of paste