Hasn't responded back, that'd totally suck if LCS was the issue.
Ofcourse that's worst case scenario, there are a handful of super easy simple fix solutions for reasons why a G5 can and will exhibit such behavior.
Try resetting the PRAM?
Remove the battery?
Reset the SMC ( I think that's what it's called, check acronym, sorry off the top of the head) via motherboard?
HDD could be incompatible with 2.7 G5?
Never know, but if there WAS A LCS leak, then I'd bet money that's the issue