but it is probably also possible to unlock the boot loader and then replace the boot loader itself with one that merely pretends to be locked. How would you know the difference?
Sure, in theory, but doing that would require advanced knowledge, it’s not something a random shady seller on eBay would do. With skills like that, they could easily get a high paying job, or if they really want to be a criminal, a better option would be getting into something like phishing or cryptolocking, which, skills wise, is easier than writing a custom bootloader.
Obviously criminals aren’t going to install security patches for vulnerabilities that they are exploiting.
Which is why the first thing you should do is do a factory reset, update the phone, and do another factory reset. Or an even better option would be to just flash the factory firmware downloaded directly from the vendor.
Sure, in theory, but doing that would require advanced knowledge, it’s not something a random shady seller on eBay would do. With skills like that, they could easily get a high paying job, or if they really want to be a criminal, a better option would be getting into something like phishing or cryptolocking, which, skills wise, is easier than writing a custom bootloader.
Which is why the first thing you should do is do a factory reset, update the phone, and do another factory reset. Or an even better option would be to just flash the factory firmware downloaded directly from the vendor.