Updating unlocked g1
You could also install a version of Cyanogen Mod on the device, I believe that allows you to use wifi to authenticate.
I found this tutorial on how authenticate via wifi, but keep in mind, this device is a couple years old now and I don't know if the files needed are still available.
Because BIOS flashing is potentially risky, if you do not encounter problems using the current version of BIOS, it is recommended that you not flash the BIOS. Inadequate BIOS flashing may result in system malfunction.
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You will be exploiting this flaw to enable ADB access and bring up the Settings menu, from which you can enable Wi Fi and activate the device. The ADP1 device is SIM unlocked, you said you have the Developer version of the G1.
The whole BIOS updating procedure should be treated with extreme caution.
If you do not encounter any system instability or bugs with the current BIOS version, we suggest that you keep it.
But the update failed and now the problem is that I cannot boot the phone completely. Although, I don't have a T-Mobile SIM card now, I could pass that stage with an AT&T SIM card. When I press menu button it just shows me the settings for APNs.
Now it wants me to login to my gmail account to boot up. I believe in the newer versions of android, one can skip logging in to Google.