You must define the shock style?
sharp fast single "sparks" of very high voltage are often "static".
Static can't really destroy a computer easily , unless your on the inside of it. It still would be smart to touch the case metal first, before working the other buttons. It still could send power back through ports, switches, even led (leads), and rarely through insulation on low voltage wires, like mouse or keyboard.
A static shock can occur when the human is ungrounded , and creating static energy with different methods, like carpet rubs, even chair rubs, the human acts like a capacitor the energy being stored in the body. A static shock to a properly grounded case , would be normal in high static areas, with insulated humans gathering static energy. Because electronic components can be damaged by static, usually people would not want that happening around the computer at all anyway.
The main discharge of static , is usually fast sharp and ends in miliseconds, turn down the lights and you can even see a static spark jump up to 1/2" off your finger to discharge. After that first single fast discharge , The human has to charge up again, the rate of recharge and accrued energy would determine how much energy will again be discharged.
A partial discharge of static can also occur, when full discharge does not happen. through minor isulation, plastic, paint and powder coatings, past and around things to get to the conductors. Then a static discharge would repeat more often. full grounding or full discharge to a metal part of the case, would do a full discharge, and would repeat less often.
The other more dangerous shock for the humans is usually a continual flow of low cycle energy through the human, often when touching the case itself, or other metal grounded locations on the case. That type is much more rare, and reguardless of any policy , no tech would leave an installed computer that had improper grounding or ac voltages capable of flowing through a human.
If it was that type of shock , then the thing should be unplugged.
An AC power shock could be a bad (rare) problem of connections touching the wrong thing in the PSU and can damage a human , and could even cause a PSU fire. It could also damage the computer as it changes. It could also be caused by improper polarity of the wiring in the home. I have lived in one home where the polarity was incorrect in ~50% of the AC wall boxes, They say it is rare, but it was not for whomever wired up that house :-).
The AC power shocks usually are not quick , although a PSU capacitor discharge can be faster. If it was that type you would feel it continually, and if a person even thought for a moment that it was that type of shock, it should not be Re-tested, it should only be completly disconnected from the wall socket and fixed first.
Any other electrical storm feelings, high power flowing through network cabling, or phone cabling, or powered speakers, and monitors, or anything else would also be wrong, could be dangerous to both electronics and humans. It could be a home wiring problem, below ground wiring problem, and hundreds of other things. All of this would also be something that should be determined what it is, and fixed, not tested by repeating shocks, used or guessed about, because it could involve serious power.
Is the case Light with CCT (cold cathode)? A cold cathode lighting curcuit, could also provide for a higher voltage , many of the Cold cathode lightings for computers are very cheaply made, and certannly could have a defect (mine did). They can throw a good shock, would be continuous , could pass power through the case, and/or to other wiring. If that was the problem, the computer would be unpluged, then disconnecting the cold cathode lghting curcuit from the power could test for it.
LED only case lighting does not use higher voltages, and would not exhibit those symptoms (without a defective PSU problem existing).
(CCT lighting can also exist in Monitors)