Windows 7 - Laptop won't start after restart.

I have an Asus K50IN laptop, which I recently took apart to clean it from dust, during that I screwed apart the cooling system, hard drive, SD card reader chip and CD/DVD-player device. (And I just took them apart from the PC, not individually apart, so that I could just be able to reach more places inside laptop's interior.) Then I put everything back the way they were, and also applied new thermalpaste to CPU and GPU. When I turn the PC on, it goes OK, works all the way 100%, but when I restart it, it boots 'til the Asus logo, but then suddenly shuts down, when I start it up again from Power switch, it also dies at almost the same spot, and this process continues as long as I restart it right after previuous crash. Now the interesting part is that when I let my laptop rest for a couple of minutes for example, or even couple of tenths seconds, it starts OK, and everything works. But as soon as I want to restart, this scenario happens again.
I have freshly formated Windows 7 which worked just fine, but then I took it apart, and this restart-startup problem occoured. And when it wants to shutdown then it will, it doesn't matter if I reach BIOS menu, or boot menu, with F2, F12 keys on my pc. I have done startup repair but no use.
Any help would be appreciated!

hi and welcome to the forum

Does the problem occur when plugged in and or on battery?

As the issue you have in a pc is normally power supply related or motherboard.

When a computer shuts down, the capacitors drop there charge to a low enough level to shut the computer down, but when it restarts it doesnt drop the voltage as far, which causes the system to reboot. Im thinking there is a problem there. The resting period you describe would also point towards is, as it would allow any residual charge to dicipate.

It happens both with and without battery. Your theory seems quite logic, but what would them be the solution to this?