FRF85B to FRF91 Build:
(Alternatively, you may also do a *#*#CHECKIN#*#* in order to get to FRF91 once you are on FRF85B)
Also, for anyone looking to get to FRF85B from an older build (GSM or AWS):
ERE27 to FRF91:
ERE36B to FRF91:
FRF50 to FRF91:
EPF21B to FRF91
1. Download the update from one of the links above.
2. Rename the file to update.zip. Note that if you're using Windows, just rename it to "update" (no quotes, of course) because it's already a zipped file.
3. Copy the update.zip file onto your microSD card.
4. With your Nexus One off, hold down the trackball and press the power button.
5. You'll be booted into a white screen with three Android robots on skateboards. Select "Bootloader."
6. On the next screen, select "Recovery."
7. Your phone will reboot, giving you a picture of the Android robot and an exclamation point inside a triangle.
8. Now press the power button and volume up button at the same time. It could take a couple of tries.
9. Now (using the trackball this time) choose "Apply sdcard:update.zip" and let things run their course.
(Note: Before doing step 9 you can also run the "Wipe Cache Partition" option. This has been known to help with the soft key accuracy on the nexus one (optional. This causes no data loss.)
By Popular Demand (Credit to lox):
Update.zip to flash with custom recovery
This is the totally stock FRF91 repacked as update.zip. The radio hasn't changed since FRF50, so if you are using it, you can keep it and install the noradio version.
- without radio image: multiupload (md5sum: 041b1e21433e636340ca6b56f141a315)
To root FRF91, just flash this update.zip (contains busybox, superuser.apk, su, unsecured boot.img) (md5sum: c6c27598c210576792d6d56738a2edde)