CMOS reset (502) - no working solution yet

[Tarbikos]

Hello,

I'm asking for help with my HP Pavilion Gaming Laptop 15-ec2900nc (53M45EA). About a month ago it shut down on its own and wouldn't turn on. It always just turned on the light for a while, but after loading the "HP - auto repair in progress" screen, it immediately turned off. (only one cooling propeller was spinning) When I tried replacing the battery with a new one and tried to turn the laptop on, it was the same.. one time out of ten attempts, "CMOS reset (502)" appeared. I tried following the instructions from HP support to recover the system BIOS. I don't know if I found the correct restore file, however via the "hold windows button + B + power button" method I restored the BIOS (probably) and it showed me the message: A system BIOS Recovery has occurred - BIOS recovery (500).. after pressing it nothing happened and I was back to square one.
I don't know what to do, plus I already bought a battery which is probably useless. Do you have any tips on how to fix the laptop please?

Thank you in advance, Thomas

[BeemerBiker]

Can you run diagnostics?
Tap the ESC key after powering on to run diagnostics.

Do at least one pass through memory and disk diagnostics assuming it starts up.

If you cannot get into diagnostics then needs to be serviced.  Get an estimate.

Click here to check warranty
and
Click here for world-wide contact info

[Tarbikos]

I can turn on diagnostics, BIOS, etc. without any problems, it's just that if I don't turn any of it on, the computer shuts itself down immediately.
I ran the diagnostics. Memory and disk are fine.

[BeemerBiker]

As shown in this disassembly video, there are two fans.  You have both a GPU and a CPU and the system will shut down if too  hot or (I am guessing) if one of the fans is not spinning at right speed.

https://www.youtube.com/watch?v=KR-hXtur_ww

That you did a bios recovery with these problems and did not brick you system is amazing luck.

Before any bios update one should run diagnostics.

On power up fans normally spin at top speed a flew seconds then drop down to idle.  I believe the BIOS checks to verify the fans are spinning at startup and shuts down if not.  You might use an air duster to ensure the fans spin and don't quickly stop because of dust bunnies.  Was the system recently serviced such as replacing thermal material? cpu upgrade? a power glitch?

[Tarbikos]

I think... I have a bigger problem right now. I disconnected all the components in the video, cleaned them up and put them back. Including removing and blowing out the processors. As well, I washed the old heat conductive paste with alcohol and put in new. After putting it back together, the laptop did not turn on. Nor did the charging light come on. I don't realize what I did wrong. I used gloves, blew everything out with sterile compressed air.
Do you know what I might have done wrong?
There was some big sticker on the RAMs, I removed that, but that's probably not the problem 😄

Otherwise, the laptop has had a similar problem before. My wife had it repaired by a local friend, and he supposedly just cleaned/blown the laptop (he didn't change the hot conductive paste).

All components are original including the charger. I just replaced the battery yesterday.
I still want to ask about this thing.. didn't find the purpose anywhere, but I guess cooling?

[BeemerBiker]

If the power LED does not turn on possibly cable popped loose.  If you removed the hard drive and then put it back possibly it dislodged the ribbon cable

The power jack is at the top right and the ribbon cable to the motherboard is as shown.  The disk drive fits on to top of the cable. Check to see if it is connected properly.  This is what it looks like.

[Tarbikos]

Unfortunately, I tried replacing the charging connector because it was outdated and looked ruined. I also tried reconnecting all the ribbon cables, but none of that helped. The light still doesn't come on when I plug in the charger. Even when I hold the start button for a long time, nothing happens. Could something else have caused this? Maybe I damaged the processor while cleaning the old paste?
However, I would be happy if it was a minor fault.
Thanks so much for trying to help me.