AB2001TR

I'm having trouble setting up burst fire modes. I'm holding down the trigger whilst on single fire mode and the MOSFET doesn't emit the beep sound after 10 seconds like it's supposed to do so. Anyone know what I'm doing wrong or what the issue might be? Any help would be appreciated:)

I'm having trouble setting up burst fire modes. I'm holding down the trigger whilst on single fire mode and the MOSFET doesn't emit a beep after 10 or so seconds confirming that 3 round burst has been applied. Does anyone know what's going wrong with this or if I'm going something wrong? Any help will be appreciated :)