01.Download the factory reset firmware.
If you have the USA version download this file: HappyNewYear.zip
If you have the UK version download this file: HappyNewYearUK.zip
) = 4f0efb2037524a06bda26f286bba474d
) = b253b71fad2ed0352bcb58c4966b9a25
02.Connect your G1 to your computer and mount the SD card.
03.Backup the content of the SD card.
04.Format the SD card to FAT32 mode.
05.Unzip the zipfile and copy the file DREAIMG.nbh to the SD card.
06Rename DREAIMG.nbh to DREAIMG.NBH (might also work without the capitals…, but better save than sorry).
07.Unmount the SD card.
08.Unplug the USB cable.
09.Turn the G1 off.
10.Hold the Camera button and press the Power button to start in bootloader mode.
11.Press the power button to start the downgrade to RC29 USA or RC7 UK
(this takes a few minutes, dont interupt the progress)
12.After finishing, softreset the G1 to reboot (Hold Call, Menu and End).
If everything went well, you are now a proud owner of a rooted G1. Sign in with your Gmail account. If the login fails, you might need to add your APN settings (use the Menu button to add a new APN profile)