Hi Cedric,
This is an odd coincidence, considering there's no reason to disconnect the display when changing a battery. Did you use isopropyl alcohol to loosen the charging coil? That shouldn't be an issue unless you somehow flooded the entire inside of the phone and it leaked through to the display. Even then, worst case it would have caused some edge bleed on the LCD, but it wouldn't have damaged the digitizer even if it got in there.
Assuming you don't have a sudden screen failure, my guess would be that the display cable got jostled in the process of replacing the battery and isn't seated correctly now.
If it was my phone, I would open it back up and check the display cable. Unplug it (after unplugging the battery, of course) and reseat it.
[image|2765275]
Reconnect the battery and turn it on and see if it's working again.
If that doesn't do the job, come back and update your question with the results and we'll go from there in trying to help you get your phone going again.