Dell Vostro 3750: BIOS recovery after flashing modded BIOS possible?

[el spelunko]

I followed these instructions

https://www.insanelymac.com/forum/topic ... fi-clover/

and flashed my innocent 3750 with a modded UEFI-capable 3450 BIOS-update after reading "This guide is valid for 3750 though as its virtually the same machine as 3450 only with 17" and an added secondary HDD feature". Now the machine is still bootable but the fan is permanently running at full speed, the keyboard number pad is no longer supported etc. So I would like to recover the stock BIOS. The usual doubleclick on the executable BIOS downoaded from Dell ends up in the message quoted below.

There is a recovery method that should generally work for a 3750:

https://lazyadmin.nl/it/bios-recovery-d ... te-failed/

But in my case after entering the commands I get this message:

"Platform system ID and platform name check error: Running on an unsupported system.

System BIOS Upgrade Information: Cannot find any matched product in supporting list!

Current System BIOS Information:
System: Vostro 3450 (1241)
Revision: A13
Vendor: DELL SYSTEM"

and no files are extracted. My interpretation is that the actual BIOS is checked and after finding a 3450-BIOS no 3750-files are generated because they could damage a 3450.
So I don't know what to do now.

[edwin]

This should get you on the way:
https://lazyadmin.nl/it/bios-recovery-d ... te-failed/

[el spelunko]

Thanks but as said I can't extract the .hdr- and .rom-file.