Used Surface pro not a surface?

[taz1967]

Hi
I just bought a used surface pro 4, well, I think. I have tired to find out what it is. The Model in system info says it is a ST15? I cannot run any surface pro 4 firmware/driver updates because the does not report it as a surface? Was there alternative bios out there? Any ideas on how I can fix it?

Thanks in advance!
Jim