Hello
Quick update- after doing various shunts, I could manage to turn on the display again with the help of sebastien79. He was right - the problem was not from some parts, simply the CC chip wasn't getting power information.
Then I tried to look at what happened. Basically, I did many damage on the motherboard board during the screen hack attempt, because of the flat cable that is connected to the inverter : the flat connector is loose, and I saw the cable getting off while the Z was powered. I then noted nice sparkles - must have happened before :-) (When I first saw the cable out of the connector, I though I had forgotted to plug in it, and my memory was failing me)
Such shorts may be the reason why the touchscreen chip and the flat cable that conducts backlight information seem to be dead. This may also explain why at some moment I could not even power it at all - the cable must have shorted something inside.
Played with the diagnosis menu - the nand seems also to be dead (can't do a restore, but it reports no errors on nand check), but it may have been before.
Basically, I now have a zaurus dead as can be - even as a screenless terminal. I am in the process of purchasing parts to try to at least revive a zaurus out of the 2 I killed during this hack attempt.
I will now document the hack, explain how it failed, and why it can't work, but basically - it is *not* possible with that generation of Zaurus to replace the 3.7 screen by a 4" screen. They are physically the same (more or less one millimeter) but electrically totally different : every connector has its own size and wiring and you can't find a possible way to hook up anything.
Also, pay attention to these tiny screen connectors - neuroshock knows first hand they are fragile. I believe now they can cause great damage when they are not properly working - a strong weak point.
At the moment, my best advice for the screen hack is to let it go. But I'll try to convince you guys with color pictures :-)
Guylhem