Battery light blinking all time, bios can't recognize any battery, CMOS reset (502)

[Falcomaster]

Hi
I have several problems that I think are related.
Before all the events, my laptop was lost at the post office and returned to me after half a year, without a hard drive, RAM and power supply.
The battery was completely discharged in these half a year.
I installed RAM, a new m.2 ssd, bought an HP power supply.

After the first launch, a CMOS reset 502 error flew out. I installed Windows, but Windows does not see the battery, showing that the battery is just connected and charging, but not showing the percentage of charge, the charge indicator lights up yellow for 5 minutes, then flashes white all the time. In Bios it is also impossible to see details about the battery, in the field about the battery there are only zeros. Laptop won't start without power supply. Every time after disconnecting the power supply and reconnecting it, a CMOS reset 502 error is displayed after start.

I thought that the battery had died after such a long time. I ordered a new battery and plugged it in, but that didn't help. The battery has a charge (I turned off the power supply during operation and the laptop does not turn off), but still the BIOS and Windows do not see its details, the charge indicator lights up yellow for 5 minutes after connecting the power supply, then it flashes white all the time. The laptop with a new battery will not turn on without a connected power supply, when you press the power button, nothing happens.

What I have tried:
I updated the BIOS 2 times, to the latest possible version for my laptop, version 27, once from a flash drive, once from Windows.

I disconnected the battery, held the power button for 15+ seconds and reconnected the battery and connected the power supply. All the same. I did the same with the battery connected.

I launched the diagnostic application from HP and chose the battery test, the test ended with an error.

Removed the battery in the device manager and restarted the computer.

I think that there may be a problem with the CMOS battery, because if you turn off the battery even for a minute, then after that the launch starts with a 502 CMOS reset message. But I carefully studied the motherboard from the side that I see and its photo on the Internet on the other and the manual for use and did not find the CMOS battery either in the instructions or visually.

Does my laptop have a CMOS battery or it use the main battery for that?
What else can I do?

[erico]

Newer model laptops like yours use current from the main battery to supply power to the CMOS, so no (RTC) CMOS battery.

PartSurfer shows no CMOS battery

https://partsurfer.hp.com/partsurfer/?searchtext=5YH30UAR&searchby=product

The CMOS 502 error is checksum invalid, which means that part of the BIOS ROM file that is read when the notebook starts is corrupt and that is why it won't boot to the storage drive.

Does the battery charge when the notebook is off?

I suggest trying one or both of the two methods that are descriped on the URL below this line
https://support.hp.com/us-en/document/ish_3932413-2337994-16

[Falcomaster]

No it won't chargee when the notebook is off, did the same, 5 minutes yellow, and then flashing white.

[erico]

OK.

Recovering the BIOS is the way to go then. That may get it to work again.

It is a shame that someone in the post ofice disassembled it and liberated important parts before it was returned to you.

They may have done more damage than you think.

[Falcomaster]

I've tried the recovery, the process passed well but the problem still continues. Battery is not charging and blinking white.

[erico]

Have you tried both methods described on the web document?

I found that the USB flash drive worked for me on clients notebooks in the past.

You should also be aware that the Windows key + B method has its issues. 

It is not mentioned in the BIOS recovery documentation, but sometimes it requires holding both keys down for about a full minute before a notebook's BIOS responds with a recovery dialogue on screen.