How does it beep? Did you look at the manual where it shows what the different tones mean?
Let's start here- Have you programmed it yet?
Your batteries need to be fully charged or it will not recognize the proper cell count (that you set it to during programming) at startup and it will just beep.
If the above are correct then if you connect a battery with a different voltage to run with (ie a 3s lipo instead of a 4s) you need to re-program the "cell type" section or the same over/under voltage error will occur as before and you'll only get beeps.
ATM that's all I can come up with. Maybe others will chime in.