Your power supply is browning out. The brown out may have already turned into a blown supply. If it was just a fuse, the only problem you would have experienced would be the inability to turn the unit on.
However, you were experiencing problems with functionality too. The MPC is just like any other computer, multiple voltages are required to power the CPU, the peripheral bridges, etc. Your supply was missing a voltage...causing the unit to prompt for the OS disk. Now the unit won't turn on period, so it would appear that the entire supply is shot.
I would recommend that you take it to a repair shop that specializes in M.I. repair, not just your average TV or VCR joint.
If it requires repair, shouldn't cost more than $150; of replacement is required, you might be able to get a used PS for $200. New power supplies for a 2000 run about $400.00. My bad, these are Canadian dollar quotes, do the math for USD.
Peace.
The Shadow
One of Three
The Special Projects Division
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