Hp dv6 1308EL stuck on HP Invent screen

Hi all,

I've had a problem with my notebook.

I've unmounted it to change the thermal paste on CPU and GPU, and now when I power it it gets stuck at the HP Invent screen for a loong time.

How can I fix it?

I've tried to change the thermal paste again, and it was ok.

I've resetted the CMOS

I've tried separately the two RAM cards

I've tried to boot it without the hdd

BUT nothing happened..

Even the BIOS screen, when I manage to get to it, it's veery slow, I can barely navigate in it..I've resetted the Bios settings, but still nothing..

Help me please, I'm going crazy!

And I forgot to tell that the first time I booted it, it worked fine and I used it for a few hours and it was going just fine!

After I restarted it, with no updates, it didn't boot anymore..