Laptop keeps restarting before entering the BIOS

[Twan_Baten]

Hi all,

I have a HP Pavillion DV6000 laptop here that does not boot. When I turn the laptop on (by using the hardware button), the front led lights up and the fan (top-left) begins to spin, both for only 2 seconds. Than the laptop seems to shut down (both the fan and the led light turn off). After 5 seconds the the laptop turns on again (led and fan). After a 2 seconds it turns off again. This repeats endlessly. 

I have already:

- Reset the CMOS (by removing and reinserting the battery with a break of at least 30 seconds)

- Power reset the laptop (https://support.hp.com/ph-en/document/c01684768#c01684768_removablebatt)

- Removed all RAM (I know that the computer should not boot then, but it should also not be turning itself off and on again, right?) 

- Removed 1 (of 2) RAM cards and mixed up the slots

- Cleaned the fan. I did not clean the motherboard or anything, but it does not seem to be damaged or dirty.

Notes:

- It does not matter whether I have the battery connected or removed while just using the power adapter.

- Pressing the power button while the led and fan are turned of does not influence the repeated sequence. To turn the computer completely off (without removing both the power adapter and the battery) I have to hold the power button for +-10 seconds.

- The laptop lacks many screws (appearently someone else removed them in an effort to repair the laptop). I don't think that the important ones are not there.

I think the problem has to be some short circuit in the power module or some early part in the motherboard, but I am clearly no hardware expert. Does anybody have a clue?

Thanks in advance,

Twan

[Lil_Boy_Blue]

Hi
First:- Turn off the computer, press and hold the PWR button for 4 seconds.

Then - Leave only keyboard and mouse connected, disconnect all externally connected
devices such as Docking Station, USB storage devices, displays, and printers.
Unplug the AC adapter from the computer.

Next - Press and Hold the Power button for 15 seconds to Hard Reset.
Rinse and Repeat

Power on your PC, press Esc (repeatedly), then F2 at the prompt.
Choose System Tests (Fast Test does a 4 minute hardware check).

[Twan_Baten]

Hi Lil_Boy_Blue,

Thanks! I followed your steps, but they didn't make any impact at all. The screen does not even turn on.

These steps look a lot like the steps provided in: https://support.hp.com/ph-en/document/c01684768#c01684768_removablebatt which I followed before.

Any other tips?

[Lil_Boy_Blue]

I cannot suggest anything you haven't already tried.