@AndyYan,

Just a theory: if you enable R&D mode and disable LG resers then the next time you boot the X server will most likely die (because of the bad libxau lib) and hopefully the phone will not reboot.

The problem is that you won't have a shell, or even a visible framebuffer, meaning you won't be able to even blindly type in the necessary commands to restore the working lib.

Try it anyway, and PLEASE report whatever result you get.

As an alternative, you might want to try putting the "Rescue OS" on a microSD card and boot from it using the flasher.
Link: http://talk.maemo.org/showthread.php?t=75369