Follow the control path
The radio sends commands to a receiver. The receiver communicates with the flight controller using the supported protocol and configuration. The flight controller combines the commands with sensor information and controls the aircraft through its motor controllers.
A fault anywhere along this chain can look like “the drone is not listening.” Separate the questions: is the radio connected to the receiver, and does the flight controller receive the right channel information? Binding and correct flight-controller configuration are related, but different, checks.
Follow the picture
The camera supplies the view to the aircraft’s video system. Compatible receiving equipment supplies that picture to your display. Hardware, firmware, antenna connections, configuration, and the environment all affect the result.
Do not diagnose the entire aircraft from the video alone. Some display information is generated through another connection between the flight controller and video system. A picture with missing on-screen data can be a different problem from having no picture at all.
Understand their separate limits
Control and video equipment can report different kinds of link information. Learn what your own indicators mean, which warnings you have configured, and how the manufacturer describes degradation. Do not reduce everything to a single distance number.
Your aircraft’s loss-of-control behavior must be configured and checked using the instructions for its system. A video failure is not something a flight controller can always identify or fix for you. Treat both links as things that need a plan before a flight.
Troubleshoot one chain at a time
If you have no radio input in the flight-controller interface, follow the control chain. If control input is correct but the display is blank, follow the video chain. Use a simple record of what works and what does not. Changing receiver settings and video settings together makes the next observation less useful.
For powered bench work, follow the equipment’s precautions, including removing propellers where specified. Stop when you reach a step you cannot verify. A methodical question beats an enthusiastic guess.
MAKE IT USEFUL
Your next small job.
Draw the control path and the video path for your kit. Label the exact devices on both sides of each connection.
Go straight to the source.
These official resources support the next step. Hardware, firmware, and local requirements can differ.