Having done some more testing, I found the issue. The Debian based live CD that I'm using to apply the updates was missing the libcurl4 package, which is now required for the latest versions of the BIOS (and iDRAC) Linux firmware files. After running: apt install libcurl4 everything worked ok.
Has anyone successfully updated the BIOS of an R250 or R350 using the latest 1.3.3 BIOS file under Linux. (BIOS_VXY4H_LN64_1.3.3.BIN) In the testing I'm doing, the update looks like it's going through ok, but then displays TargetCompareState= Before prompting to reboot. On reboot, the BIOS doesn't update. [IMAGE] If I try and update in an automated fashion by running BIOS_VXY4H_LN64_1.3.3.BIN -qr  the system appears to lock up, before (I think) the watchdog timer kicks in and does a reboot. If I extract the 1.3.2 and 1.3.3 BIOS files and compare the contents, I can see that the BiosVerifyLinux.bin file is missing from the 1.3.3 bundle. Not sure if that is part of the issue. Any pointers welcome... Cheers,Rob
R250 / R350 1.3.3 BIOS update under Linux