You are likely here because you are growing impatient for a slow, unpredictable OTA update to your phone. Or, even more likely based on this post’s tags, you are already unlocked and rooted, possibly running CyanogenMod and want to experiment with Froyo.
Nandroid Backup before doing anything.
Update: After rolling back to Cyan 5.0.7.1 from Froyo 2.2 I encountered issues with video playback and downloading from the market. Froyo uses radio 4.06 which breaks video playback (I assume some changes for streaming video) and for some reason the market was sensitive to having been accessed using Froyo. At the bottom of the post I explain how to roll back to your nandroid image without these issues if/when you want to.
Before I describe just how easy it is to get to Froyo on your rooted Rogers/AT&T Nexus One, it is important to know that FRF50 is an upgrade to both EPE54B (Radio configuration for AT&T,Rogers,etc.) and ERE27 (Radio configuration for T-Mobile,etc.). Knowing that you could brick the Nexus One by using the wrong radio configuration delayed my migration to FRF50 as there was a fair bit of mis-information out there to begin with. It is good to know that bricking based on radio firmware is probably a thing of the past for the Nexus One now that there is a single build for all carriers. Also, moving back from 2.2 to earlier releases, even via nandroid, will break video playback and the market temporarily, so if you need to keep your Cyan Apps2SD partition skip to end to see what issues may arise.
If you have not unlocked and rooted your device; start there perhaps with Amon’s process. It is simple, unlocks great capability and may not void your Hardware Warranty according to some posts I have read. If you are not rooted, then just hang on for the OTA update.
Once you are rooted, simply install ClockworkMod ROM Manager. It is awesome, and makes moving between various system and recovery ROMs trivial. I paid for the premium ROM manager last month which adds some extra ROMs and features; I am not sure what the limitations are on the free version these days.
A Froyo stock image (unrooted 2.2) became an option on the ROM Manager last week, but I didn’t notice it. If you do find a ROM that you like that isn’t on their menu (Cyan, AmonRA and others are all there) then you can just download it, and let ClockworkMod manage the install. This is what I did to install a Froyo 2.2 pre-rooted ROM with radio from Modaco forum I found on the Internet without wiping any data.
Here is how I upgraded my N1 running Cyanogen 5.0.7.1.
- Click here to download the ROM
- Open the ROM Manager app on the N1
- Choose Install ROM from SD Card from the options
- Select the downloaded ROM on the N1 filesystem
- Optionally choose to Backup and/or Wipe the Device (I didn’t)
I have included a series of screenshots below. The first three show the process I executed last week to upgrade to 5.0.7.1 from 5.0.6 installed the old way, and the last three screenshots show the process described above in this post to install the rooted 2.2 Froyo ROM from my sdcard after it was downloaded through the browser. As you can see, it is soo easy and much safer with the ROM Manager.
ClockworkMod manages the entire process using its own Recovery ROM (which it flashes onto your device when you first install or use it to manage ROMs). If you like to do things yourself via the Recovery, you can boot into Recovery, execute Nandroid Backups and load ROMS directly from an update.zip placed on your SD card in a very similar manner to other Recovery ROMS (which Clockwork can flash for you too).
My direct upgrade to a root’d stock 2.2 from 5.0.7.1 appeared to work just fine, except I did not have access to my sd-ext installed applications. It turns out the Cyan Apps2SD method is not supported. So if you use sd-ext, there will be an issue accessing your installed applications, at least for now, as I am not interested in wiping my phone. I will wait for CM6 based on Froyo and for now have reverted to my nandroid backup of Cyan 5.0.7.1. The process was actually non-trivial, requiring a few extra steps I did not expect, listed below, which can be read about here.
- Restore your Nandroid Backup from Pre-2.2
- Use ClockworkMod option Install ROM from SD Card to install the the 4.04 radio downloaded from here
- Use ClockworkMod option Download ROM to re-install 5.0.7.1 with the Google Apps selected and also Wipe Data and Cache selected (Your photos and sdcard data are safe)
- On reboot to the wiped device, re-login to the Android Market. Downloads will be working again (this fixes the market)
- Using Clockwork Recovery Image (power on with volume-down, select recovery, then nandroid) restore your nandroid backup
After this process, you are right back where you started.
More information is in the links below about some of these roll back issues, and Froyo tips.
Froyo Radio update breaks video playback
Issues with the market downloads
Setting Froyo to force apps to install to SD, like in Cyan but not to ext4.
Bernie’s Froyo Workaround Links and Info
