Dell Alienware 17 R1 / M17X R5 / LA-9331P REV 1.0 - 7 beeps

[zwect]

I have this Alienware 17 laptop with the VAS00 LA-9331P REV 1.0 motherboard that does not turn on anything when power is plugged in and gives the 7 beep sequence, CPU / GPU does not heat up, i tried only with an I5 4200M (the laptop did not come with either the GPU or the CPU, but on the back says that it originally came with the Nvidia 860M and an 4710MQ).

While i do not know if there is any CPU blacklisting system on the motherboard, i tried reflashing the BIOS (at UH14) and the EC (at U2) accordingly but no changes either.
PCH doesn't seem to be shorted but i haven't done any further testing since this could be something else, i saw on some posts on the internet that this beep sequence can be related to some other issues too.

I also tried with an 570M, a Quadro 3000M and an 7850M but neither of those seemed to change anything.

[zwect]

Small observation: upon using thermal cam, nothing except for U1 and 4 caps connected to the speaker (LA12, LA11, LA9 and LA10) emit a glow but no noticeable heat up on them either when touching.
U1 > C8051F347-GQ

also 5V and 3.3V seem to be present as seen on U1's first 8 pins

[mcplslg123]

First check whether you have ram and VCCSA voltage present? Is 3VS/5VS generated?