when you say Hewlett Packard, is it a laptop or a desktop?

If it's a desktop, then you should definitely unscrew the case and have a look inside.

Problems with power supplies are usually very very easy to solve and it's not really worth even paying an engineer to fix it. Often just a case of the screws coming lose and the PSU (power supply unit) slipping a bit. Or a case of one of the cables from the PSU to the motherboard coming unstuck. Fixing a problem like that is like putting one Lego brick on top of another.

if it's a laptop of course, that's an entirely different kettle of fish and I wouldn't know where to start.