Refrig is cold in top section, warm in bottom drawers.

I see the fan working which blows cold to the bottom.  With the top drawer out, you can bring on the fan by pushing in the bottom drawer only! Guessing it should not work that way.:) 

There are two [U]sets[/U] of drawer switches. One pair for each drawer.  Somehow one of the switches for the top drawer is frozen with ice, and peaking behind the back panel, I can see ice built up beside that one switch. I imagine we need to get that one working.  What would have cased ice right there only= and no where else?

Once if get that working, I', guessing I need to see baffles open and close - if I can get to them. 

[U]Are the baffles which control the top/bottom air flow, accessible through the top section with the big door, or through the bottom section with the drawers?[/U]

I see 4 screws which appear to hold in the back panel behind the two drawers plus a few screws at the top, near the fan.  I've removed all of them, but the back panel won't come out.  It is loose at the top and on the right, but something is holding it?  Any tips are much appreciated.:)