TASCO STARGUIDE 114 WITH MISSION CONTROL

My list of things to check would include:
1) Batteries - they usually fail whenever the temperature drops. And that does happen outside as you are viewing. They appear fine when tested by a voltmeter, but fail when any actual "load" is placed on them. If you have an adapter which plugs into the mains, I would go with that instead.
2) Cables - they can become frayed and "open" with wear. Connectors (especially the RJ-xx telephone type) are notorious for maintaining good reliable contact.
3) Proper placement of connectors - ie Know your telescope; read the manual. No manual (?) then check the labels/function and fit of all jacks/connectors BEFORE APPLYING POWER. In case this step has already been skipped, check for blown fuse(s) which may save your investment.
4) The computer requires some basic information about your location and local time before it can begin to determine which objects may be available for viewing. Again, this will require some reading of the manual. Your information needs to be only somewhat accurate (within a county for position, and a few minutes for the time).
5) Get help from a local amateur - Learn to use the telescope without the computer. Your optics do not depend on the computer to give you pleasant enjoyable hours of viewing. Finding objects in the telescope without the computer is challenge enough. Adding the extra burden of learning how the computer works can be frustrating. Once the un-computerized telescope becomes familiar, then tackle the computer.

I know, you've already tried all of these! I hope you are enjoying Saturn by now!