While not impossible, you have to try fairly hard to fuck up your phone like this. I'd be actively impressed if your story is true (particularly as you used the plural), and if so I'd like to know what they were specifically trying to install that fucked up their phones.
It's just statistically more likely they downloaded a malicious app from the Play Store than had any chaos side loading.
I appreciate how weird this comment is if you don't know what computers used to refer to...
It's also a good example of how you very much can have technology replace jobs.