Working Dell E5440 will not flash BIOS

[UzY3L]

Hello,
I'm trying to update the BIOS on a *working Dell E5440. I say *working because it always takes about 30s to boot.every single time (cold-boot and restart) and it will not accept a BIOS update using the methods I've tried.

I have even used a CH341A programmer to flash the BIOS but anything else than the original BIOS doesn't work.
Here are my attempts:
1. https://youtu.be/inaXR9DGH5c
2. https://youtu.be/ZTwDcCTyVng
3. https://youtu.be/J8abV-ZKdAw

The steps above have been re-created in both 32 and 64 bit versions of the following:

Windows XP
Windows Vista
Windows 7
Windows 8
Windows 8.1
Windows 10 (most builds, from 2015 to present)

Ctrl+Esc+ power adapter doesn't work. I have no idea how to fix this. Please help