DS Doesn't turn on

I swapped motherboards from 2 DS's because the R button wasn't working. The first DS works fine but the second flashes the power led and bottom screen for a second when I hit the power button. I tried swapping out batteries and charing but it didn't work. Did I kill the DS?

 

Check your screen connections. They may not be connected properly or one screen has gone bad.

 

Yea, I fixed it after a an hour or so. The ribbon cables needed to go in very tightly, a lot tighter than my other DS.