You mean Zt-280 C91 I guess? Could you provide more information - like what happened for the screen to stop working - C91 has a capactive screen - which is influenced by temperature - could have to do sth with this (but I don't really think so). Are you sure your screen doesn't work at all, or is it from time to time. See if you can manage to try calibrating it (though I don't imagine you'll be able whithout the touchscreen, of course you can try plugging a mouse in the usb hub - go to Settings->Screen Calibration).
Need more info. Screen doesn't come on, so is the tablet itself on? How do you know?. When you turn it on to you hear that little speaker pop sound you hear letting you know the sound is working? Have you tried to update the firmware, have you hit the rest button? We need info in order to try and help
There was a lose ribben during the manufacture process. Iphones have the same issue sometimes. Glad your husband is a handy man, most people dont have the small phillips screw driver to take the back off.