Versions like (RC33 US firmware or RC8 UK firmware) then u Need to Downgrade.
To Check Firmware Version Do the following without Sim
If Phone Re***** then u have version RC29 or Lower, Skip Upgrading/Flashing Procedure.
(Flash your phone to RC29/RC7 or lower to be able to Exploit Root Access)
Step 1- Format the SD card to FAT32 (Make Sure of this, otherwise it wont Work.
Step 2- Unzip the RC29 or RC7 image file (DREAIMG.nbh) to the SD card & Rename it to (DREAIMG.NBH)
Step 3- Switch Off the Device then Insert the SD card.
Step 4- Now U have to Put your G1 in BootLoader Mode (Hold Down Camera Button, and press Power Button) DO NOT DO ANYTHING TO INTERRUPT THIS PROCESS.
Step 5- Press Power button to Start Upgrade/Flashing Procedure.
Step 6- Once its done, Reboot your G1.
For Those with RC29 or Earlier Versions, Just Follow The Below Guide.
You must have ADB installed on your Computer (Extract to C: Drive), Download & Install the USB drivers. U can Manually Install when Computer Asks for the Drivers once U Connect your G1.
1- Plug your G1 & Install Drivers.
2- Without Sim Card in Your G1, <enter>setprop persist.service.adb.enable 1<enter> Even though u dont see what u typing, but u are actually executing a Command on your G1 to Enable USB Debugging in Settings.
3- Once u Execute that Command USB Drivers will be Installed again, but this time will be recognised as ADB Interface.
4- Click Start>Run>cmd> to Command Prompt
5- Type c:\adb devices (If your Device is Connected u will see it)
6- Restart your G1 but now With Sim, to see the Activation Screen then Plug USB Cable & Type c:\adb devices (to make sure u are connected)
7- Type c:\adb shell (U will see a $ sign) Just Copy & Paste this into Command Prompt (am start -a android.intent.action.MAIN -n com.android.settings/.Settings) The Settings Screen will Appear, now Switch on Wi-Fi & Connect to the Internet.
8- Now u can either Login with your Existing or Create New Account with Google.