My son touched an electric plug (does not have a cover on during renos) with a metal rod which slipped while trying to use it to turn on the connected light switch. Huge spark which burnt a hole in the rod as well as left a mark on the metal near the light switch. Do not believe that the rod went into the plug , but may have touched some wires near/ behind. Does this imply some sort of open wires that may be in incorrectly or just the very obvious need to cover everything? I don't want to just cover it up to discover that we have missed something that may be wired incorrectly. The boy has received a HUGE talk re electrically safety, but other than a good scare is fine. Thank you.

Could be he just touched the side of the plug. BUT, in my house, with my kids, if I wasn't certain, I'd have it looked at by a qualified electrician. It won't cost much, but will give you peace of mind at the least, and possibly find a hazard. Is it worth $100? Could be any number of things. Poorly grounded outlet or box, defective outlet. Did the breaker trip? If not that should be looked at. A dead sort, and an arc of that size should've tripped the breaker.

Does the receptacle still work? "touched an electric plug" I think you mean receptacle and not the plug.

This did not trip the breaker and everything is still working.

Could have caused serious injury. All covers should be on even during reno-only 2 small screws!

Have the outlet checked by a professional. Keep the children out of the reno area, and treat all live outlets as that, LIVE.

Any wiring involved and exposed during a reno should be shut off.

You may want to review a thread showing what electrical short can do:

https://www.askmehelpdesk.com/electrical-lighting/all-do-yourselfers-why-electricians-wear-protection-690640.html