Quadra 605 fails to boot snapshot

Much like Andersen Silva reported to this list in February, I have a
Quadra 605, upgraded with a full 68040 CPU (*with* FPU), and it fails
to boot the OpenBSD kernel (3.6-GENERIC), printing exactly the same
message "[ using 407118 bytes of bsd a.out symbol table ] " and then
hanging.  Pressing Cmd-Power (which generates an NMI, and drops to the
debugger in MacOS and NetBSD) does nothing whatsoever (which I suppose
makes sense, as the kernel hasn't started yet).  Cmd-Ctrl-Power (the
3-finger salute) does a soft reset as expected -- I don't know if that
key combination can even be trapped.

The bsd.rd kernel from the -current snapshot (3/26/05) fails exactly
the same way, aside from printing a different number of bytes.

It seems no one ever posted a follow-up to that thread about trying a
-current snapshot, so I am posting this message.  My Q605 has just
36MB RAM and is running Mac OS 7.6.1, but the error appears to be the
same.  Incidentally, NetBSD-2.0 runs just fine on this machine; I can
provided a dmesg output from NetBSD if requested (obviously there is
no dmesg output to be gathered from OpenBSD, as it halts after that
one line).

-Andrew