I have a Inspiron 15 3585 running Ubuntu 20.10.

I am trying to flash the bios.  I have downloaded the bios from the dell support site for this machine although it doesn't show this version of Ubuntu.  

I followed the instructions and loaded it on a Fat32 Flash drive and hit F12 at startup but it gives the Invalid File! error.  

One thing is I am booting legacy mode.  When I installed Ubuntu initially that was the only option I could get to work.  

Not sure if I need to boot with UEFI mode or not.  I have tried to enable UEFI but the computer won't boot up.  

Any help would be appreciated.