somehow the BIOS I loaded was for a Surface Pro 4
Yikes. I don't really want to even speculate about fixing that. But in case it will help here is my BIOS details (without the SerialNumber)
wmic:root\cli>BIOS list /format:list
BiosCharacteristics={7,11,12,15,16,17,19,23,24,25,26,28,29,32,33,40,42,43}
BuildNumber=
CodeSet=
CurrentLanguage=en|US|iso8859-1
Description=2.05.0250
IdentificationCode=
InstallableLanguages=1
InstallDate=
LanguageEdition=
ListOfLanguages={"en|US|iso8859-1"}
Manufacturer=American Megatrends Inc.
Name=2.05.0250
OtherTargetOS=
PrimaryBIOS=TRUE
ReleaseDate=20150410000000.000000+000
SerialNumber=<redacted>
SMBIOSBIOSVersion=2.05.0250
SMBIOSMajorVersion=2
SMBIOSMinorVersion=7
SMBIOSPresent=TRUE
SoftwareElementID=2.05.0250
SoftwareElementState=3
Status=OK
TargetOperatingSystem=0
Version=OEMA - 1072009
According to BIOS /? there is a BIOS Create function but no Set function. I don't know what that implies exactly but I would be hopeful that Create might have the same effect as a Set (or perhaps Delete + Create would).
HTH
Robert