Billmac is Back!
Update: Billmac is back to Apple Repair straight away.
All I did was installing the t-mobile mobile broadband software from the official disc. It was booting and all before install, and simply installing one official software can cause it not to boot. Orz.
Update: Billmac was fixed very quickly
So I sent Billmac back to Apple Repair on 2010-12-08, and I just got a phone call today 2010-12-15 from an Apple Engineer. He found out, correctly, that the problem was caused by the t-mobile software. He also found out it's the official t-mobile software disk replacing the crucial libcurl file named libcurl4 (library file for URL related work, used everywhere) of the OS X 10.6 was replaced by the official t-mobile CD. He managed to revert this and make Billmac works again.
He also told me I can pick up Billmac from Regent Street, London today. Wow, one week repair was impressive, especially it's right before Christmas.
Still, a network library caused a mac not to boot is just bad.
One "Like" for Apple today. =]
Billmac was born late 2009, and joined my family in May 2010.