No. 1: Please make sure the Audio cable is connected to Aux input if car has Aux input.

No.2: Please check the android factory setting (code is 2018)- Aux switching mode- SET Manual,  then choose the Aux in OEM radio and go back to android see if auido come out.

No.3:  Please make sure the original CD is powered on.

No.4: if there is no sound still, please check the optic fiber relocation, the video guide :
https://youtu.be/v3aBtKBVrjo

No.5: Please double check the connection of android plug to original radio to make sure it is well connected.