how does one do a factory reset if the home screen is still locked?
You'd boot the phone into recovery:
1. Power off phone (ex. hold power button and select power off or pull the battery)
2. Hold Volume up, Power, and Home buttons at same time until you see the model number, then release buttons
3. Phone should boot into recovery (little Android guy laying on his back with belly open)
4. Use volume down key to select/highlight "wipe data/factory reset", press power button to confirm selection
5. Use volume down key to select/highlight "Yes delete all user data", press power button to confirm and it will start factory reset process
6. Once done it will return to recovery with "Reboot system now" highlighted, press power button to confirm/reboot
Or see this video: