Vmware host server R720 currently on bios 2.2.2, attempting to update 2.7.0

formatted USB to fat32, copied bios to USB drive (after renaming it bios270.exe) and inserted USB into server.

pressed F10 during bootup into get into Integrated Lifecycle Controller, select firmware upgrade

Upgrade fails with this error:

"Unable to verify the digital signature of the update package (SUP0525)

recommended action:

download the latest supported update package from your service provider and retry the operation"

 

what am I doing wrong?