[iBook] dead display

[Howard Pettigrew]

Greetings iBook listers
A teaching colleague has just come around with her G4 14"iBook. She  
was working on her school reports when her screen developed problems.  
It suddenly cut out to 1 second screens of red, green, blue, etc.  
When she bought it around, it fired up okay so thought I would repair  
permissions and do an Open Firmware reset, not really believing they  
were the problem. But then the colours struck (I've never seen this  
before - nvram fault/ logic board?). After leaving it with the  
battery out for 30 mins, I tried an Open Firmware restart, then tried  
plugging in an external monitor (just stays black) and also tried  
Target mode (doesn't show up on other machine).
One thing I did notice was that it has no start up chime.
I left it for a couple of hours and tried it again. When I opened it  
up (I think it may have been left going but hard to tell) the fan  
started and ran for an abnormally long time. Then I tried to start it  
in Open Firmware but although I was holding down the kyds, it started  
normally. Unfortunately, I didn't have the user's password and so I  
had to ring her. I got this off her and started to drag stuff off  
onto an external drive. I had just got the precious reports off and  
was trying to grab all her other documents when it went into the  
coloured screens again - red, blue, green, grey, black, cycling  
through endlessly. I have now shut it again in the hope I can get a  
little more off it. It seems to go for 3 mins before going into this  
cycle. I'll try timing it next time. Any thoughts on the problem and  
solution?
This particular school has had an incredible run of problems with  
their iBooks. This teacher is on her second after endless problems  
with her first and it is only 16 weeks old. Another teacher had 4  
logicboard repairs until they replaced hers and the Principals was  
also replaced. I wonder about some bad practice in their use of their  
laptops. I understand that there is a design fault in the hinging of  
the screen putting pressure onto the logicboard. I have always  
encouraged kids to either have the screen fully open or shut, not  
'play' with the catch opening and closing the lid as they are prone  
to do. Any thoughts as to why they have been so beset with problems  
and possible solutions. This is only a 8 teacher rural school and the  
young teacher in charge of computing is tearing her hair out coping  
with the number of computers she has to take in for repairs. These  
are all 12" / 14" iBooks.
Cheers