first ill try to post a picture ASAP but here is the mayor point i turned several nigths from now my Ds lite, and i turn it off around 3 days after only to find it has on both screen several lines that form an oval, last game i played on it was golden eye DS the obvious questions are what is it? and how the heck i fix it?
if it looks like that the lcd is crumpling or darkening on the center/line, breaking it's heat damage on LCD's post a screenie, happened on several of my old GBA's. but till we see a screen can't tell for sure.
the best way to put is that near the center of the screens there are two patters made by several vertical lines forming on oval