why haven't you supplied the main board with 3.6v's? sometimes i come across over sized 3.6v pram batteries i just solder wires to the +/- and then just a dab of goop and stick the battery in another place on the main board.

first things first, get voltage to the pram, if you had other macs i would suggest trying another hard drive, i'm thinking the hard drive is bad, witch is totally common, these scsi drives are old and going bad all the time.

also, try to get more then one mac, then you are enabling some trial and error, with out spare parts you cant do much.

but then you might have to change your user name