It's good to have a vulnerability some times.

A couple years ago someone lent me an Android phone to do some development on (it had some hardware feature I didn't already have on my testing phones). I don't use my main google account on dev phones so I promptly set it up with whatever google generated for me and I forgot both the email and the password.

6 months later I have to give it back, and I hit reset to defaults. Surprise! The phone asks me for the previous account and password!

Back then the feature was new, which is why I didn't know about it. Fortunately, being new it was also buggy.

I managed to complete the factory reset through a complicated process that involved going through accessibility options, replacing some system apk with an older version (via adb i think) and some other trickery that I forget. But the stuff was mostly in the open on youtube.

This being strictly a dev phone, I had no data to lose. It only had on it apps I was working on and thus I had the full source code in git. Still, it was good to not create more ewaste.

I've been paying attention on newer test phones though. I don't think that security feature is as easy to bypass these days...