There’s a cool trick one of our techs recently used to force the BIOS update when you can’t use a power adapter or the battery.
Basically, you can target the .exe in command prompt followed by /forceit.
For example, Inspiron_7500_Silver_5400_1.3.1.exe /forceit
It will open the file and skip the power checks. Very useful for drain battery scenarios where BIOS needs to be updated to charge.