#1 What happens if the power is out and you need to enter your home?
It's powered by 4 AA batteries, so no problem in the event of main line power loss. If you let those batteries die, it's still possible to use the lock with a 9-volt battery.
Google
Owner manual PDF of Google RB-YRD540-WV-605 Lock Polished Brass Electronic Deadbolt Lighted Keypad.