Was there any shock damage that you are aware of? Any other kind of damage or any notable change you remember around the time the failure occurred?
Do you get any sound out of the speakers?
Does the "outside" keyboard function properly?
There's one connector on the main board in the "base" unit (the side with the QWERTY keyboard) and that has a flex-circuit that goes through one of the hinges to the boards in the display unit (the other side, with the two displays and the smaller keyboard.) If it were something simple, like that connector being dislodged, then any or all of the functions of the display unit (speakers, outside keyboard, and both displays) might be affected.
However, that connector is held in place by the case cover on the base unit, so it really shouldn't have any way to just "come out".
Given that, if it were *just* a broken display, I'd advise that it is possible to replace the display module, although if you're trying to do it yourself, I'd recommend having some electronics repair experience. I had an enV3 that was been damaged twice, and both displays were cracked, but it was otherwise fully functional; I was able to restore it by replacing the display module with a $38 unit from eBay. See this thread
for a little more detail.
However, I'm confused by your comments "otherwise in perfect working order" but then later: "reception has gone fuzzy...cannot make outgoing calls." If it were truly *just* the displays, (and especially if there was a shock event involved...) I'd say a replacement of the display module *might* do the job. But given there are other issues, I'm not as confident that just replacing the display module has a good probability of solving things.