Dell Precision M6500 not booting

So, I have this problem where all of a sudden my laptop turned off and when trying to power on again (unplugging power cable and plugging again, as I don’t have the battery) and now it’s state is the following:

I hear the gpu fan spin for about 3-4 seconds, power led on during the fan spin, and the fan stops along side the power led turns off, less than a second after it starts to power on again and just keeps on this loop.

Power led on and fan spins for about 3-4 seconds and turns off, less than a second after does the same again.

What I’ve tried so far:

1: Replace Ram or try only one module.
2: Use another cpu (originally chipped with the pc).
3: Resetting CMOS battery.

I don’t know what to do at this point, I know it’s an old laptop but it’s the only laptop I have and urgently need it running again, I don’t have any desktop pc or another pc really, just this laptop, currently I cannot afford to buy another pc.

Any help would be amazing, thanks in advance!