I purchased a ZTE Z970 MetroPCS phone from ebay sold as "For parts - Broken". The battery was drained completely when I received the phone. When I charged it for a bit and tried the Power + Volume Up key, it kept rebooting upon reaching the first Android logo. There's nothing I could do. I tried all key combinations and it just keeps rebooting.
Magically, after charging again for the second time, the phone boots up. But the seller put in one of those pattern based lock screens. I emailed the seller via ebay but the seller doesn't know the unlock pattern himself.
I connected it to the computer to see if I can access ADB but no dice. Now the phone is up at the lock screen and I do not want to restart it and attempt to go to recovery as I'm afraid that it won't boot up again. What can I do to either get around the lock screen or somehow reset the phone some other way?