Can't recover BIOS, stuck in CMOS reset bootloop

[coreutils]

Hello HP Community,

I'm seeking advice on an HP Pavilion x2 (10-n100na) that I'm troubleshooting for a friend. The laptop consistently struggles to boot, displaying a 502 CMOS reset error when it does manage to power on. The issue appeared spontaneously, with no clear cause, as the device was working fine with a Linux ISO before this problem arose.

Symptoms & Troubleshooting Steps:

• The power LED indefinitely blinks white; after multiple attempts to power on, it either fails to boot or shows a 502 CMOS reset error.
• The device's response to power attempts is unpredictable, with a 25% chance of showing the error message; other times, it doesn't turn on at all.
• After reconnecting the battery, a white LED on the motherboard lights up for 5 seconds.
• Multiple disassemblies and reassemblies have been performed, indicating that battery disconnection and reconnection gets rid of the blinking LED and has a higher success rate of booting (although it boots to an error)
  
  

BIOS Recovery Attempt Process:

1. Preparation: Initially extracted the BIOS files using WINE on Arch Linux and placed them onto a FAT32 formatted USB drive. After this method didn't initiate BIOS recovery, I prepared the USB drive again using a Windows VM, following HP's guidelines.
2. Execution:
   • Disconnected the laptop's battery.
   • Held the power button for 15 seconds to discharge any residual power.
   • Reconnected the battery and AC adapter, then inserted the USB drive.
   • Pressed and held Win+B (also tried Win+V), then pressed the power button. Upon the screen powering on, I released the power button while continuing to hold Win+B.

Outcomes:

• The laptop often fails to boot, with the LED entering an indefinite blink until I disconnect and reconnect the battery.
• Occasionally, it progresses to display the CMOS Reset 502 error but does not boot further.

Given these persistent issues and the boot process's unpredictability, I'm reaching out for insights or recommendations. Is there a known resolution for such boot behavior, or could this indicate a deeper hardware issue, perhaps with the motherboard or power supply circuitry? Any advice on further troubleshooting steps would be greatly appreciated.

Thank you for your time and assistance!