PLEASE HELP!! Black screen after BIOS update failed

[Alabama35121]

Let me start by saying thank you to all replies as I am currently at a stand still.  I have a hp 15-dw0038wm notebook.   Here is what happened (sorry for the long story):

It all started with a failing hard drive.  I installed a new hard drive, which I tested using OEM diagnostics and all passed, and installed a fresh clean install of Windows 10 ver 1903 then upgraded to 1909.  After installing all drivers and software, upon restart a message came up about the hard disk smart test failure and requesting that I install an operating system.  I pulled the drive and retested using OEM diagnostics, all tests passed.  So at this point I'm thinking maybe a BIOS updated would solve the problem and mine was behind on the BIOS updates.

I reinstalled Windows 10, using Legacy mode in BIOS because it wouldn't recognize the drive in UEFI mode.  Once booted to Windows, I downloaded and attempted to update the BIOS.  Here's where I believe I went wrong...a message stating that the BIOS "might not" complete properly in Legacy mode came up and gave me the option to update anyway.  So, of course, I selected to proceed anyway.  It looked like it was working as it began the flash of the BIOS.  But when the computer restarted...nothing but a fan spinning and a black screen.  Any suggestions would be greatly appreciated.

[stevecomputer]

https://www.youtube.com/watch?v=qpiGUojtr3E

This might help.  

[Alabama35121]

Hi Stevecomputer,  Thank you for your response.  I tried these steps using 2 different BIOS & 2 different USB drives.  I tried using the key combinations "Win" key + B, "WIN" key + V, B by itself, V by itself.  I tried the USB drives in both USB 2.0 ports & in the USB 3.1 with an adapter for my USB drive.  None of this worked.  Is there any other known key combinations or other suggestions you might know?  Thanks in advance!

[stevecomputer]

A teardown video is here:

https://www.youtube.com/watch?v=nF9ryZd59ss

Only try if you are confident. I can't see the cmos battery in this video, if you open yours you could remove it and try starting with it out. You could try removing the dvd drive, and the hard drive and the ram to force an error into the bios.  Unplug the battery before any work also.  

[Alabama35121]

Unfortunately, I have it apart but there is no CMOS (Coin Cell) battery in this system.  Any idea if there is a jumper point to reset CMOS?

[Alabama35121]

I am beginning to suspect the motherboard has failed but not sure at this point.

[stevecomputer]

I can't find any battery or jumpers in the videos either, and I can't see jumpers either, this is new to me I must admit.  did you try connecting it to a tv or monitor to see if there is any output?

[stevecomputer]

https://www.youtube.com/watch?v=zjAZ0DTX3aI

May also help. At this stage it's worth trying anything.

[Alabama35121]

Yes, I tried using the HDMI out port and still no video on external monitor.

[stevecomputer]

That's bad luck. Perhaps there is someone local that could solder in a new bios or reflash it using a jtag onto the board(if the board supports it)