Here is the binding procedure for F4 1S Brushed FC (SPI Frsky) . The FC is used on Beta75S and Beta65S

Note:  Please make sure the setting in Betaflight is correct. If there is confusion about setting, we suggest you flash the Cli that we shared in our website. 

How To Bind:

1) Connect the drone with battery, then press the bind button. Receiver LED (green) is on, which means entering the binding mode. 

2) Choose "BIND" in the transmitter.

3) Binding is successful when receiver LED (green) flashes.

4) Power on again, receiver LED (green) is on, which means bind is successful and quad is functional.