1. Install the ROM Manager on your Micromax Bolt A27. Get it from Google Play Store, then install the clockwork mod recovery.
2. Connect your Micromax Bolt A27 to your PC employing the USB information cable. Copy the “Micromax Bolt A27_4.0.3 ICS/Ice Cream Sandwich.zip” file you downloaded to the SD memory card.
3. Restart your device in the recovery mode using ROM Manager. As soon as in Recovery Mode, go to ROM Manager and select backup / restore to back-up your information.
4. From the Recovery Menu do a total data erase (including Delvik Cache). When completed, go back to Recovery Principal Menu and choose Flash ROM from SD Card. Navigate the location you copied the ”Micromax Bolt A27_4.0.3 ICS/Ice Cream Sandwich.zip” file and follow the directions for installing Android 4.0.3 ICS/Ice Cream Sandwich on your Micromax Bolt A27. As soon as the installation is over, just reboot your Micromax Bolt A27 device, and here you go, you’ve just upgraded it to the new Android 4.0.3 ICS/Ice Cream Sandwich. Thank you for visiting Upgrade/Update Micromax Bolt A27 to 4.0.3 ICS/Ice Cream Sandwich