I cant charge mine. it keeps making a beep

Please check user manual it should be battery/ups failure

Two possibilities come to mind. 1) The battery has failed and can't be charged fully (usually one cell fails and it won't charge fully). I've diagnosed this by removing the battery and trying to charge it with a variable power supply. You can try replacing the battery.
2) The UPS itself is faulty and can't charge/maintain the battery. The entire unit should be replaced.

I recommend solution 2. I had the 725VA in this consumer UPS line and when I replaced the battery, the UPS could not keep the battery charged with any load on the unit.

Check your warranty, though. The APC warranty is for 2 years on this model.

I hope this helps.

Cindy Wells