lombard powerbook G3 help

Need some help. I have a 1999 Powerbook G3 Lombard (bronze keyboard) model and recently it powered-down and won't start up, even from the ac cord. Took it into a repair facility and the technician said "through the tricks of the trade" he was able to get it to power up, but it would be a minimum of $400 to fix. He then said I was better of buying a new one, and he would take the old one off my hands for $100. That led to suspicions. I have tried to power it up using that little reset button on the back, but need more help. I remember the date and time had to be reset often and the lion battery didn't seem to charge either. What else can I do, or what "trick of the trade" did this guy know. Any help would be appreciated, as I cannot afford a new one or would like to at least see if I can fix this one at a minimum cost.