I can do basic electrics, I will take any electrical/electronic appliance apart and "have a go" as my background is in electronics engineering.
I have no fear of these things because it is all relatively logical, and if it's already not working the worst case will be "it's still not working, but now I have a pile of spare screws" or "Smoke came out, please refill"
Plumbing though, hmmm water leaks make a mess. And don't stop when you flick the off switch.
The nearest I got was pulling the hot-water boiler apart when it randomly kept tripping the earth leakage on the fuse box. That turned out to be a chaffed wire on the exhaust flue fan intermittently earthing itself out, to ages to find, and I had replaced the mainboard, regulators, cut out's and most other things before it was spotted.
Live and learn.