HP Envy x360 Convert 15m CMOS Reset (502)

[Mike157703]

After a hardware repair for a screen replacement and following all steps correctly in the repair manual (including shutting down and disconnecting battery before attempting any repairs) the computer started up with a CMOS Checksum is Invalid error, CMOS Reset (502). With the ability to press Enter to restart the computer. The BIOS was not corrupted prior to the screen repair.

After that the device seems to remain in a locked up state / blank screen with the power LED remaining on (no POST screen either). 

I was able to perform the recovery steps to reinstall the BIOS through downloading (sourced by serial number to ensure the correct file, F.16 Rev.A ) and following the Win+V and Win+B methods of recovery from a USB. Following all on-screen prompts, the system was able to correctly detect the USB and rebuild the BIOS image. It goes through the entire process without any issues and indicates it was correctly and successfully installed and to press a key to continue. 

Unfortunately after this it will loop back to the same behavior as above (blank screen). I'm able to navigate into the BIOS, system info, recovery, system tests, etc. I've verified all boot settings (tested removing secure boot and setting bios back to default), as well as trying to manually UEFI boot (via F9 boot menu) to the properly-detected drive / source with windows boot manager and it simply returns back to the blank screen. I've also selected (via F9) a different bootable (verified working) Windows 11 USB drive and as soon as I select that - it will once again return to the blank screen.

I ran a long system self-tests as well where all components passed.

I am at a loss for what is going on. Is the BIOS not actually the problem here and it's something else? Any other ideas? 

[Nal_NR]

Hi @Mike157703 ,

Welcome to the HP Support Community. 

I'd be glad to help you! 

I'm sorry to hear you're encountering this CMOS error after your screen repair—issues like this can be unexpected and frustrating, especially after following all the correct steps.

If you have followed all the steps from this document and still having issues, this unit might need service. 

Keep me posted for further assistance

Please mark this post as “Accepted Solution” if the issue is resolved and if you feel this reply was helpful click “Yes”.

[Mike157703]

Yep, I've went through all of the relevant 500/502 steps. Thanks for the references though!

After I posted this, I went ahead and reinstalled the old screen just to see what would happen and sure enough it was able to successfully boot to windows.

RMA'd the replacement screen. Despite working during BIOS/etc., it's possible there's a slight defect (more power draw once progressing to boot? Above my pay grade/knowledge level), or some other glitch that's causing the system to hang up once it hands off and moves to the boot phase.

If a second screen results in the same issues, we'll look at sending the device in for repairs. I'll update here once I receive the new screen and attempt the repair again.

[Nal_NR]

Hi @Mike157703 ,

That's fantastic! appreciate it. Do keep us posted. Take care