Android phones have a recovery mode that lets you access the bootloader and wipe data if you're unable to normally boot your phone.

If you forget your Android lock screen password, is there a way to unlock your phone? The short answer is no – you will have to factory reset your phone if it's locked to be able to use it again ...

The Android Recovery screen should then show you several options like Reboot system now, Reboot to bootloader, Apply update from ADB, wipe data/factory reset, wipe cache partition, etc.

Wiping your Android phone with a factory reset might not be enough if you're planning on trading it, here's how you can prevent data recovery ...

Your data may be corrupt." The Android recovery screen prompts the user to perform another factory reset, creating an endless loop that doesn't resolve the issue.