I just ran into an issue where I FPT flashed a bad bios on a bricked board, and it posted anyway. I couldn’t understand how that happened. The only thing I could think of is that there was enough in that bad bios to draw from a backup on the OS SSD.
From everything I’ve read, you can’t modify just the bois section (from the Dell update) and successfully flash it. You’ve got to flash the full bios. So the only thing I can think of is that your bios “recovered” from a bad flash.
I looked more closely at the results of the UEFI-Editor run with your modified bios. Under 0x800A Maintenance - BIOS Recovery, it doesn’t look like the values changed, so I’m assuming that’s what happened - and what happened in my situation also.
You could change that to not recover, but I’m pretty sure you’ll brick your computer.
From everything I’ve read, you have to pull a full bios, modify the full bios, and then flash. My desktop has a service mode pin that should allow for a full FPT bios dump and modified bios flash. I’m guessing that your laptop does not, so you’ll have to dump and flash with a CH341A programmer.
Edit: I’ve had a tough time FPT flashing a full bios. Having no service mode pin will make flashing a Dell even harder.