Is my iBook REALLY dead?

Question

G4 iBook 1.33 (mid-2005) 12"
Suddenly within 2 - 10 minutes of booting perfectly, I'd get the 4-language gray translucent alert telling me to hold down the Power button and shut down. Through testing I determined it was some sort of hardware problem. I took it to a Mac store (not an Apple Store) to have a diagnosis. The guy just called and said it's a bad logic board. He said that the reason it works perfectly and then crashes after a few minutes is that once the iBook heats up, whatever is wrong with the logic board is triggered. He said I need to replace the logic board. I don't know squat about logic boards but my intuition tells me that either they work or don't; can it really be that a logic board works perfectly until it reaches a certain temperature and then it doesn't work at all?
iMac G5; iBook G4; Mac Mini G4   Mac OS X (10.4.9)  

Answer 1

As I mentioned in my own thread, the best price I
could find on the repair was at DT &
T Computer Services in Fremont, California.
They will fix it for what you would pay for just the
logic board, and they have a six-month warranty on
the repair.
I'd be afraid of buying a used one for fear it would
be the same story.
I think I'm just going to sell it for parts. I could probably get $250 for it. For that plus $550 more, you can get from the Apple Store a refurbished MacBook 1.83GHz Intel Core Duo - White
13.3-inch glossy widescreen display
512MB memory
60GB hard drive
Combo drive (DVD-ROM/CD-RW)
Built-in iSight camera
http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore.woa/wa/RSLID?nplm=FA 254LL/A
I think the money is much better spent here than on a repaired 2005 iBook.