Here's their link.

by R. Proffitt Moderator - 2/1/12 1:50 PM

In Reply to: response by shenryo

http://panasonic.jp/support/global/cs/dsc/download/index.html

Remember that I never supply how to instructions on firmware. I defer to the maker every time.

Reset is noted widely but here's one link.
http://www.amateurphotographer.co.uk/forums/showthread.php?86059-Panasonic-Lumix-G1-Factory-Settings-Reset
Bob