I have a CyberPower 425va surge protector/battery backup that is beeping every time I send a document to the printer. The printer is a Brother TN-420. What could be wrong?

SOURCE: CyberPower 325SL won't work...

NEVER mix surge protectors and UPS!!!. Doing so overloads whoever of the two gets connected to the wall. This equipment is built to be plugged DIRECTLY to the wall. Your unit just crossed it's inner battery. Take it to a recycling center, then stop on your favorite electronis shop and buy a new one.

SOURCE: CyberPower 325SL backup system

That's a tell tale sign of wornout batteries. They last about 3-4 years in a UPS like this. Here's a replacement: http://www.batteryinternational.com/cyber-power-cps325sl-ups-battery-ups-batteries-f1.html

SOURCE: I've got this battery back up/surge protector

try holding down the power button until it turns on. I had the same problem and this turned the plugs on. good luck.