Mending is so good, and as a Cantrip you don't even need to be a practiced caster.

You can't mend to fix magic smoke problems. Though it would be awesome to run your finger along a cracked screen to repair it

Mending was my first thought, admittedly because of Harry Potter And The Natural Twenty. D&D munchkin gets mis-summoned into Hogwarts, and spends a few hours every evening doing all the stuff the rules as written say his character can fit into an evening. He's still incapable of any magic the school teaches, but now he's got a bag of tricks a mile deep, and his robes look fucking incredible.

Why stop at electronics. I would think just going to a scrapyard and repairing machinery or vehicles back to working condition would be massive.

Take 20$ in scrap and turn into hundreds of dollars by repairing.