Recovery Mode

From CyanogenMod Wiki

Recovery Mode is a special environment that you can boot into for troubleshooting and upgrading purposes. It's not "Safe mode", but rather more like the hidden partition on some mass-market PCs that let you restore to factory defaults.

The Recovery Mode is loaded from the recovery partition of the internal memory on your phone. You can flash a recovery.img onto it using flashrec (if you're on Android 1.5 or earlier) or from fastboot or within a rooted rom using flash_image. Typically this is one of the first steps of rooting, as the stock recovery does not let you flash unofficial roms. Once the stock recovery is replaced with a custom one, your phone is effectively rooted and you can flash any ROM you want.

To boot into Recovery Mode:

1. Turn your phone off.
2. Hold the Home and Power buttons simultaneously until the phone powers on.
3. The phone will boot (continue holding the Home button until you have booted up).

If you've done everything correctly, you're now in Recovery Mode, and depending on what recovery image you have loaded on your phone, you'll have different options available to you.

To exit Recovery Mode, reboot by pressing the Home and Back buttons, selecting reboot from the menu, or typing "reboot" and pressing <enter> in the Console.

If you use the console on CM-1.4 recovery, entering the 'recovery' command will give you the menu back.