Custom Recovery is a program that allows you to install Custom roms(a fully standalone version of the OS) and Custom Kernals. If you want to know about the advantages of installing Custom roms then click here.
To install Custom Recovery your Phone should be rooted first. In order to root your phone your phone should be running on Android version 2.2.
To check your version goto “settings” and select “About phone”.
If you have a latest version then you can follow my guide to downgrade your version. How to downgrade your firmware (Lg Optimus one p500)
Download, extract and copy the files below to the root of your SD card
Download a Terminal Emulator from the market. This application lets you run Linux command line utilities on your Android phone.
When you open Terminal Emulator and type “su” without the quotes it will ask you for superuser access. Grant the app superuser permission by selecting YES. Now you will see a # sign.
Type all the commands given below without the # sign
# mount -o remount,rw -t yaffs2 /dev/block/mtdblock1 /system # cat /sdcard/flash_image > /system/bin/flash_image # chmod 755 /system/bin/flash_image # mv /system/etc/install-recovery.sh /system/etc/install-recovery.sh.bak # mount -o remount,ro -t yaffs2 /dev/block/mtdblock1 /system # flash_image recovery /sdcard/recovery-RA-GNM-thunderg-1.1.0.img # reboot recovery
The command highlighted in red will show error in some phones. Just Ignore it. Its normal.
After successfully executing all the commands your phone will boot into Custom Recovery mode because the last command was “reboot recovery”.
To boot your Phone into Custom Recovery mode anytime, switch off you phone and press and hold the vol_down + home + power buttons.