Hi folks!
Thanks for your earlier replies about Brahms and his console!

My guess is that the POST is failing - I hear a couple of whirr-clicks as
the tape-drive is tested, the disk-drive spins up, and then a chime (?!) and
then "...all the rest is silence". The LEDs at the top of the CPU case read
as follows:

LED with single dot under it:             Green
LED with three dots under it:             Orangey-red
LED with SCSI(?) symbol under it:  blank
LED with DDS symbol under it:       blank

On the CPU card itself, the "Term power" LED is on, and the "SCSI self-test"
LED is off.