if you can afford it, get a basic af chromebook or something inexpensive and do only purchases on it.

Check for a keylogger, change your passwords on a diff computer and don’t use it on that one until you’re 100% certain. Setup your bank to alert you for any purchases.

But he could have more fun if he didn’t lose a leg from a battery exploding.

I don’t recall any mercury being in such phones.

Hope you removed the batteries before smashing.