Below are modified instructions for Android 1.5 update/install:

  1. (Make sure the G1 is fully powered or connected to power)
  2. For Android 1.5 Cupcake download the update from: http://android-dls.com/files/ota/signed-kila-ota-148830.de6a94ca.zip
  3. Rename the downloaded file to “update.zip”
  4. Connect your G1 to your PC; mount the device
  5. Copy update.zip to your microSD card (the root directory)
  6. Shutdown the G1
  7. Start it again while holding down the Home key until you get a triangular caution icon next to a phone (this is after you see the normal G1 logo)
  8. Press ALT-L; this will open a menu of options, one of which is install the contents of “update.zip”; press ALT-S to start the installation
  9. Wait several minutes while the new firmware is installed; don’t touch / mess with the G1 — leave it alone!
  10. You’ll eventually be asked to push the Home and Back keys again; Back is near Home — not the Delete key on the keyboard; this will restart your Android device
  11. The firmware will be copied into ROM (this takes a couple of minutes or so)
  12. Your G1 will reboot itself

Good luck!

Disclaimer: if your G1 explodes during the installation process, I’m not responsible!

ceo

P.S. Adapted from / via: MobileCrunch.