If only the Left Earcup has audio but the noise cancelling in the right earcup switches on(music/Bluetooth audio is audible in the right earcup) then confirm that the position of the Mono/Stereo dip switch is in the correct position. If the right earcup has audio but the left earcup does not then first confirm that the headset is the correct way around, if the headset is the correct way around then send the headset in for servicing.
If the batteries always go flat between flights (only if you don’t fly everyday) then test the auto shut off by removing the headset from the aircraft and switching the module on. The module should switch off between 5 to 10 min if the Bluetooth is not connected to any device(LED must flash purple), if the module does not witch off then send the headset for servicing.
If the headset is not visible to the device that you wish to connect it to, confirm that the Bluetooth LED is pulsing purple(search/pairing mode), wait a few moments after switching the module on for the Bluetooth to enter search/paring mode. If the headset is still not visible then recycle power on the module. If the Bluetooth is still not visible then send the headset for servicing
If the headset creates a pulsating sound that mimics the pulsing of the power or/and Bluetooth LED then confirm that you are not using Lithium, rechargeable or NiMH batteries. Use only Alkaline batteries, all other batteries may cause damage to the module.
If you can hear everyone in the aircraft but no one can hear you, or if everyone can hear you but you can’t hear yourself/them then swap headsets with someone in the aircraft and confirm that the problem transfers with the headset. If the problem transfers with the headset then send the headset for service, if the problem remains with the same person then the aircraft needs servicing.