Lucky for you, I was a computer specialist during my working life. Here is my never fails checklist for solving any computer problem.
1 Check the punch card reader. Blow on it a bit to dislodge any dust.
2 Check all the valves are OK. Any blown ones will be cool enough to touch without burning your fingers. Blow on burnt fingers to relieve the pain.
3 Nick the wife's oven gloves and reseat all the valves that are glowing. Blow on them just for good measure.
4 Check the disk drives. Press the red button on the front and the disk will spin down and you can lift the platters out. Blow on them too to dislodge any dust, debris from a head crash or dried body fluids from the office Christmas party.
5 Check the power subsystem for bugs. Anything that's black and crispy and touching the high voltage line was probably a bug that got fried and is now causing a short. Blow hard to debug the power supply.