It's probably burned-out electrolytic capacitors in the power supply section or on the logic board (to other technicians on this board, yes they do burn out - cut one apart and you'll see the paper around the plus lead is turned to charcoal). Those are relatively low-cost components ($0.40 - $1.60, depending on the size), but require technical expertise to replace (ability to change parts on multi-layer boards with lead-free solder, and observe electrostatic discharge precautions to prevent damaging the board). Burned-out electrolytic capacitors are often readily identified by visual inspection - the tops will be bulged out and often have material leaking from the vent. In the photo below, a bad capacitor is shown next to several good ones.
If this is the case, insist that your repair technician select new capacitors for high ripple current and endurance (at least 8000 hr. rating) as well as the same or better temperature rating. I've found the Panasonic FR1 series capacitors work well for this application. United Chemi-con's EKZN series should also be adequate. They may cost a few nickels more than other brands, but the money is well worth spending.
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