At the risk of repeating myself, the 3000 is an excellent (and repairable) computer. However, after 17 years of collecting dust, the connectors are notorious for becoming intermittant if disturbed.
Last week, I disassembled mine to annually blow out all the dust (causes overheating - another form of unreliable operation). After the first 2 re-assembles, I got the same indications you describe (no HD LED). After the 3rd attempt and a soft drop from 10mm off the tabletop, everything is back to normal.
This has been going on with my 3000 for 10 years. I've always wondered how many "dead" 3000s could be rescued with a thorough cleaning and a little patience.
Do you have an accelerator? I would try again several times. Maybe test boot with the cover off.
