How to install a new ROM on your Android smartphone

1. 
   

   Installing ROM Manager

   First off, you will need to install the ROM Manager app. The good news its that it’s a free one (although there is a premium version that offers more features). Open up the Android Market from your apps list and search for ‘ROM Manager’, then click the icon and install.
 
2. 
   

   Install Clockwork recovery

   When you rooted your Android device (see page 68), it’s quite likely that at the same time you installed a piece of ‘custom recovery’ software. ROM Manager will check that you have this installed and that you have the latest version that’s available.
 
3. 
   

   Back up your ROM, part 1

   Open up ROM Manager, click on the Backup Current ROM button, give the backup a name (perhaps something like ‘Standard ROM Backup’) and then click OK. You might be asked to allow ROM Manager superuser access and you’ll need to grant this.
4. 
   

   Back up your ROM, part 2

   The phone will now automatically reboot into recovery mode. The backup process can take a little while, so make sure you aren’t expecting any important calls! The recovery backs up your current ROM to the microSD card, so it’s important not to format this.
 
5. 
   

   Choose your ROM

   Back in ROM Manager, click ‘Download ROM’. This will bring up a list of available ROMs for your device. In this example we will install CyanogenMod 7, one of the most popular custom versions of Android due to its stability and wide device support.
 
6. 
   

   Download the ROM

   Choose the CyanogenMod version you wish to download – the latest version at time of writing is 7.1.0-RC. It’s strongly advisable to stay away from the ‘Nightly’ builds, as these are largely experimental. Google apps don’t come as standard, so click to download them.
7. 
   

   Installing the ROM, part 1

   Once the ROM and Google Apps have finished downloading, reopen ROM Manager and you will see the ROM pre-installation screen. Tick the ‘Wipe Dalvik’ and ‘Wipe Data and Cache’ boxes. Click OK and the phone will now reboot into recovery again.
 
8. 
   

   Installing the ROM, part2

   The new ROM will now install. This might take a little while. Once complete, the phone will reboot again. The first boot of any new ROM can take a while, sometimes up to 15 minutes, so be patient and don’t panic if the device appears to have frozen.
 
9. 
   

   Set up Google account

   Once the phone has booted up, you will then be prompted to enter your Google account details. Doing this will automatically download and set up all your contacts, settings and apps back onto the phone. You now have a brand new ROM to explore!
10. 
    

    Calibrate battery (optional)

    Plug in your Android device while it’s on and let it charge fully. Disconnect and turn off, then reconnect the power cable and wait until the LED goes green. Disconnect and turn back on, turn off again and reconnect the charger until the LED goes green again.