Totally messed up. I forgot to delete GUPDATE.GCD in memory before updating the custom firmware. After rebooting, the device boots up but lost "touch" function. That is, when I press a button, the button highlighted but no function. Tried to copy custom GUPDATE.GCD to device and reboot; still no touch. Tried to reinstall firmware by WebUpdater; still no touch. The matter is, I can't get into service mode to flash .rgn again by pressing the battery icon. How to let 765 boot into preboot mode?