Pitfalls when buying an Android smartphone without a box?

Question

Android

I am aware that an iPhone can be turned into a brick if it is stolen and access is left through find my phone. There are several questions regarding the android:

1) How hard is it to untie someone else's account from the android phone by flashing it?
2) Is it possible to reflash an android phone so that even after a hard reset, spyware remains on the phone?
3) Buying an untied phone but without a box is a bad idea?
4) If a phone without a box has already been bought, does it make sense to check it for spyware in the left firmware? How are things going with this?
5) If you perform a hard reset, then find my phone is guaranteed not to be able to find the phone, right?

Answer 1

For example, with Samsung, you can run into a leasing phone .