Question about safety for Teens working on ebikes.

So this isn't about bikes themselves so much as it is about the safety of working on one. I'm hoping you guys can help. My son and his best friend are 13. They're both young, budding engineers. My son likes gas engines, cars and 3D printing and has a workshop. His friend is a whiz at electronics. his family owns an electronics company. Together, the cobble together all sorts of electric and gas powered vehicles from scratch, bikes, motorcycles, go-karts, etc.

Yesterday they scratch built a propulsion system to replace an old go-kart engine with a 1000w, 36 volt electric motor. They built a 36v battery with a BMS system and had another board that i think was a voltage converter/transformer. They increased the voltage to 72v, the controller said it was rated for 75v. A large capacitor blew.

While I understand that this could just be a faulty board, wife and I were noticeably concerned, especially as this happened inside the garage/house. I'm also concerned that the voltages they are working with could be dangerous or potentially lethal for someone their age.

Does anyone have any recommendations for how I can keep them safe. Any videos or guides on how to work on this stuff safely? I know accidents happen with adults all the time and doubly so for teenagers.

Thanks,

-a proud but rather concerned dad