I managed to get a terminal for the VAX and figured out how to boot
it, via "BOOT DKA300" at the >>> prompt. This gave me a boot
sequence
of some sort, terminating in an OpenVMS 6.1 tagline and a "$" prompt.
actually, it sounds like you may be booting into standalone backup, since
you don't mention a login prompt...
any other devices you can boot from?