Ibook abruptly lost power and will not power on at all

I have a G4 Ibook. I have had it since Jan 06. I just got it back from having the optical drive replaced since it quit last April. All was working fine for just less than a day when it abruptly lost power and will not power on at all. The company did the repairs has trouble shot try to power it up and is arranging for us to ship it back. Any ideas of what it could be, and the likely hood it is related to the upgrade vs. a fluke occurrence that I will have to pay additional money to fix?
CG

iBook Problems

I have the same problem with my iBook. It was beginning to scare me because it was happening with increasing frequency. Today I caved in and bought a new MacBook (I can't take the risk of losing all my data!). If you find out what causes the problem, please let me know. Thanks.

I had an ibook with the same problem. It turned out to be a bad d/c in-board. Macfixit.com has a decent tutorial on how to replace it. It really isn't that difficult of a thing to fix, though it does void the warranty. It may be other problems though. My ibook wouldn't power on, then would power on, but lose power intermittently when being used. I wouldn't suggest replacing the d/c in-board unless you are sure thats it as it voids the warranty.