Back-UPS dead after battery replacement

[Anonymous user]

I replaced the battery in my Back-UPS CS 650, but after one day of use the device seems almost dead, no output, no flashing leds nor alarm sounds, only some little buzzs and strange whispers and casual briefly lighted lamps. I made another attempt with a second new battery without success. The batteries are exactly identical to the original one in type, voltage, amperage, faston size. I'm asking if someone could suggest me a test for the device, thank you!