How to upgrade to Android 2.3.X (Gingerbread) from 2.1 (Eclair) using CynogenMod 7.1 (CM 7.1) on Motorola Milestone A853 / A953 ?

Before following the below steps to flash your phone with new Cynogenmod7 ROM; make sure that you have taken all necessary backups like contacts, SMS and most used apps etc.

Pre-Reqs:
1. Your phone must be rooted before. To root the phone follow the below instructions.(http://www.krishnababug.com/2011/07/root-android-phones-motorola-htc.html)

2. Download the required below files and keep it ready from http://forum.xda-developers.com/showthread.php?t=941346
    a. Open Recovery - OpenRecovery 1.46 - BR 0.3.zip (for update OR1.46_extfs_mmcfix_update.zip )
        Download from link
    b. Google apps - gapps-gb-20110828-newtalk-signed.zip
    c. CynogenMod ROM - update-cm-7.1.0-11.10.12-Milestone-odexed-signed.zip

3. Disable_recovery_check_by_OTA.sh - Search in google and download this file.   

4. Enable USB debugging on your phone from Menu > Settings > Applications > Development and connect it to your computer via USB.

Now Create a Folder structure under sdcard root like below

sdcard
    |
    |__update.zip
    |
    |
    |__OpenRecovery
    |      |
    |      |__scripts
    |      |     |
    |      |     |__Disable_recovery_check_by_OTA.sh
    |      |
    |      |__updates
    |            |
    |            |__update-cm-7.1.0-11.10.12-Milestone-odexed-signed.zip
    |            |
    |            |__gapps-gb-20111012-signed.zip
    |
    |____ Other_Stuff
   

Steps to flash your phone with new Android build by CynogenMod:

1. Once the above tree structure is ready on your phone just power off the phone
2. While you Power on; press X button on the physical keyboard on your milestone.
3. Hold ‘X’ until you see a Triangle with an Exclamation mark on it, and then let go of ‘X’.
4. (If required ) Press & Hold the Volume up button and press the camera button. You'll be taken to Android System Recovery.
5. Using D-Pad as cursor and golden button in the middle as ‘Enter’ , Perform a ‘Wipe Data/Factory Reset’ & ‘Wipe Cache Partition’
6. Once done , apply Sdcard :update.zip.
7. You will be taken to Motorola Milestone Open Recovery Version 1.46 .
8. From menu, go to Nandroid > Backup All. This will place a backup of your current ROM in a folder called Nandroid on your SD Card.
9. Move it to a safe location later.
10. Perform a wipe data/factory reset (In case of CynogenMod updates skip this step)
11. Perform wipe > wipe cache partition and wipe Dalvik cache.
12. Apply Update, scroll to ‘update milestone-signed.zip’ and apply.
13. Now Apply  ‘gapps signed.zip’ and Apply.
14. Go back to Main Menu and reboot system
15. All set to see new CynogenMod logo after Motorola logo :) The first boot may take more time.

Possible errors :
1. E:signature verification failed error - If you get this error , make sure that the file under SDCARD > OpenRecovery > scripts > Disable_recovery_check_by_OTA.sh is fine and readable.
Note : Keep the above tree structure available always on ur sdcard and replace the new updates under updates directory each time when new updates are available.

Reference :

• http://forum.xda-developers.com/showthread.php?t=941346

• http://www.motorolafans.com/forums/motorola-milestone/31775-today-we-teach-u-step-by-step-how-to-install-android-2-3-ginger-bread-in-ur-motorola-milestone.html

• http://android.doshaska.net/cm7

• http://forum.xda-developers.com/showthread.php?t=696845