I have a Target Pro that was doing the same thing. The problem is the battery connection is very touchy. If you open the battery cover it will look like it should be working ok. Put a couple of layers of electrical tape, or any tape for that matter, cut in thin strips and installed vertically on the inside of the battery one on top of the other. They don't need to be more 1/4 in wide and 1 1/2 in long, just enough to keep the battery from slipping. Hope that fixes it for you.
I just thought of a test for that. Take off the battery cover and wrap a rubber band around the battery and the front of the front. If it works fine, then stick the tape inside the battery cover.