Did you disable the BIOS HDD settings and then tried booting? As it was said, MFM cards has its own BIOS so the PC's BIOS can do mess.

yes, BIOS HDD not installed , makes no differece - still drive not ready

When was the drive last used?

2 decades ago? I have no idea really 😁

Yeah, it looks like Low Level Format has degraded greatly. Looks like the partition is no longer existing, so I am afraid you will not be able to read data again. If you want to use the drive, you must LLF it.

Also, in debug try

1g=c800:0

If it hangs the machine, it does mean that it cannot access the memory of the MFM card. Can be wrong, but can be right since some controllers does not have the tool built in.