Swing that lever to the right and as you do the inside part of it which is against the inner back box with all of the parts attached will swing with it. Once out of the way, slowly lower the inner back board. It should be hinged together in both the lower right and left hand sides. Once in the downward position, you can change the bulbs.

Inkedbronco_6_LI (resized).jpg

If you look at the picture above, there are two resting brackets for the inner back box to rest against once lowered. Make sure yours are there. Also in the above picture, look up in left and right hand top corners. Those two brackets (possibly) need to be removed to release the inner panel as well. I've had EM's when those are in and not, it all depends who has been in there reworking things. If it is binding up while lowering it, make sure those lower hinge brackets are tightly screwed in place, do this while it is the upward position with the lever locked. Hope this helps