I acquired this older XR15 a while ago for really cheap. It supposedly was working when I purchased it (never actually tested it). I finally got around to cleaning it up and plugging it in, and the 3 buttons across the top flash between blue and red. The LED’s on the underside also flash on for a split second every 5-10 sec. I’ve never had any of these lights and am unsure how to proceed. Anyone familiar and know what I need to do in order to get it working?