XGA to SXGA problem

[tim S]

I tried changing an XGA screen to a SXGA, which should have been pretty much a no-brainer....no?
Well now I have a T40 that looks as if the backlight has blown but it hasn't, I don't think.
I had removed the XGA lid and laid it over to one side with the wireless connected.
I plugged in the SXGA lid and turned on the laptop. The screen came up, I changed the res to 1440 or whatever shut it down.
I then disconnected the wireless from the original XGA lid and completely installed the SXGA lid along with its wireless. I turned the unit on and.....nothing!
I replaced the XGA lid and still nothing! I could see info on the screens but it was as if the backlights had blown on both screens, it couldn't be....could it?
Just to rub salt in the wound, the laptop works just fine when plugged into an LCD monitor!
I have no idea what went wrong. Except perhaps, since the battery was in the machine maybe something on the MB shorted out.
Help!
Tim S