I suspect my phone is compromised, and if a simple hard reset will fix all potential problems, I'll do that. Will that solve all potential problems? I'm concerned that the guy who just replaced my phone's screen (had my phone's password) installed something dubious. He said he also adjusted or replaced one or two other components, but did not charge for them.
When I got the phone back it was fine, but an hour later when I unlocked it it was reset, no apps, photos, etc, and the keyboard had changed from English to English-&-something-pictographic, maybe Chinese. I restarted the phone and it looks normal again. But the battery is draining at twice the speed it normally does, which leads me to suspect something is happening in the background.