How long have you waited for a boot screen? Was it always this way or did you just buy it?
I have an A4000T that waits so long to boot I thought it was DOA for days until I forgot I left it on. I bought it that way. The original owner solved the problem by installing A4000D (Desktop without the NCR SCSI driver) Kickstart ROMS in the machine and sold it that way to me. The first thing I did was put the correct 40.70 (T) ROMS back in and I created the problem. I put the old 40.68 desktop ones back in and left it. It still works to this day and infact is running OS4 right now with a CSPPC.
Good Luck,
-Jeff