> Turns out that the phone was still locked, the seller had neglected to logout from his Xiaomi account. Even worse though he had forgotten his login and password.

I thought this bit was phrased a little too kindly. While it's unclear whether it was the case here or not [0], usually when you buy a locked phone off eBay and the seller has "forgotten" to log out of their cloud account and has "forgotten" their password (and login too, to boot!) it's because the phone was stolen.

[0]: OP claims "seller went above and beyond" to get the phone unlocked, which I initially interpreted as "figured out the locked account info" but then continued to read and learned that the use of an unlock tool was involved.. making me once again doubt the veracity of the "forgetful seller" story.