If you killed the internal receiver on your Mobula7 or other quadcopter with the same Crazybee flight controller you can add an external receiver. Just follow along.
This Mobula7 came with the FrSky NON-EU receiver. The video shows the troubleshooting for how to diagnose that the receiver is indeed the problem and the installation of a FrSky XM+ receiver.
Note: You will lose Smart Audio functionality.
Edit: I've been made aware there is another way to do this and not loose Smart Audio. It involves flashing custom firmware and using Soft Serial. I have not tried it, but you can check out the procedure here: https://icantfly.xyz/mobula7-crossfire-smart-audio/
Here is the manual for the EU-LBT version that shows the wiring diagram that is mentioned in the video.
http://www.happymodel.cn/wp-content/uploads/2018/10/Mobula7-Frsky-EU-LBTXM-Plus-version-Manual.pdf
