Want to manually update your G1 to some other firmware? The process isn’t that hard but you have to be sure to do it right. Free HTC is not responsible if you brick your G1 using this tutorial on how to Update your G1 firmware. Ok, now that we have that out of the way, let’s begin.

• First, rename the file to “update”
• Next, download the update or firmware you want and save it to the root of your phone by connecting your phone to your computer via usb.
• Turn your G1 off and power it back on by holding down the “home” key and pressing the power button at the same time (hold them until your phone restarts).
• keep holding those buttons down until an exclamation sign appears on your screen.
• Now press Alt + L at the same time. This will take you to the boot menu.
• Now press Alt + S to start the update process, this will take some time so just wait for it.
• When your G1 Update is complete, press home plus back as it says on your T-Mobile G1′s screen.
• Your phone will reboot.

Now you are all set. Enjoy!