Why Root? Free Wireless Tether.. enough said.
Backup
First things first, backup all system applications and data. I did this using the Titanium Backup App for rooted android phones which produces a backup on your sdcard. I then moved the backup to my pc by connecting my phone to my pc via usb and dragging and dropping the Titanium Backup folder from my sd card to my desktop. I also did a contact backup using VZ Wireless Backup Assistant for good measure (Settings, Accounts & Sync, Backup Assistant)
Unrevoked Forever
Next I had to make my current root permanent using unrevoked forever. The unrevoked forever method toggles a non volatile memory register on the radio chip. This is there by design and when toggled disables a variety of system checks, allowing custom executables to be installed.
Now that I had my permanent root installed I thought I would go ahead and accept the upgrade invitation that had been harassing me all day long. Unfortunately this did not work and first accosted me with an error message and then rebooted back into my 2.1 installation.
Downgrade
After some internet scouring i determined that I had to first replace the custom recovery I had installed when I rooted my phone originally with the stock recovery. Only then could I apply a stock OTA update. I found this android forum which provided downgrade instructions including a link to the stock recovery image in a file called PB31IMG.zip. Finding that file and downloading it was the least pleasant part of this task. You find it on free download sites that make you wait for 90-360 seconds before proceeding to download this 100+MB file at 100Kbps… sheesh… my coffee is getting cold… 20 minutes later, move it to your sdcard, reboot while holding the volume down and voila! Once my phone booted up it was back to a stock installation and all my data and apps were gone.
Pre-Upgrade Upgrade
Now that I was back to stock 2.1, I had to apply another update to get to the latest version of 2.1 prior to the release of 2.2. I found the requisite files over at xda-developers and brought my phone up to software number 1.22.605.2.
Upgrade to Froyo
http://forum.xda-developers.com/showthread.php?t=770091
Root
first re-install a custom recovery image and then apply the su update:
http://unrevoked.com/rootwiki/doku.php/public/forever
Restore from Backup
Install Titanium Backup from the app store and restore all apps and data. This brought back everything from text messages and contacts to remembered wireless passwords. Following the backup, everything wasn’t perfect… there were a couple of things here and there that required tidying up.. but all in all nothing major. Most importantly Wifi Tether still works!
