Issue UPS even OFF

Hello everyone, I come to you because my UPS is flawed. Indeed, my UPS makes a noise like clicking even when off. It looks like the clicking noise when the UPS start itself after power off. Except this time, it does it even without being ON. And, when I decide to put ON, it definitely put itself on work condition whatever there is power or not. The situation is that it can't load itself when network works. It can even stop my computer as it is always with empty battery. I have opened it but nothing abnormal at first view. What to do? Thanks

WE Nova 1000VA