I have CyberPower UPS's 1350AVR. The screens just started blinking blue. (They were a few weeks apart in starting this behavior). So I replaced the batteries in one of them, but the behavior remained.
I tried the new batteries in the other with the same result.
They still pass power and surge protection I guess.
One of them has had probably too much load on it, but I reduced it after it started blinking. The other has only had a small router as the only load.
When I press the bottom (menu) button The screen comes on for a few seconds and then it (both of them) beeps and goes back to blinking.