It appears that this UPS is failing, because it has started rapidly switching back and forth, between the status of being on AC and on battery. I've checked the power connection, and the AC itself is normal, so I need to RMA it. However, for some reason, the copy of the sales receipt I had stored on the computer isn't usable. I contacted the seller and requested a new copy, but I seriously doubt that they will provide one, because it has been over two years since the purchase., Which means digging through boxes of papers, hoping I can find the hard copy, but I'm not too optimistic. Therefore I'm probably going to have to buy a new one, or attempt to fix this one. It would be easier if it simply lost power altogether, because then I would simply look for a fuse, but I'm wondering if anyone know of a possible reason which I might be able to repair, that would cause it keep cycling on power?