The sequence you follow when wiring a quadcopter matters tremendously for safety and troubleshooting. I learned this the hard way after frying a flight controller by connecting things backwards.
Start with your ESCs and motors. Solder the three motor wires to each ESC's output pads. The order determines rotation direction, which you can swap later if needed. This gives you four motor-ESC units ready to mount on your frame arms.
Next, connect your ESCs to the flight controller. Run the signal wire from each ESC to the corresponding motor pad on the FC (typically labeled M1 through M4). Connect all ESC ground wires to a common ground point on the FC. For power, you have two approaches: either solder the red power wires directly to battery voltage pads on the FC, or use a power distribution board as an intermediary. I prefer soldering directly to FCs with integrated PDBs because it eliminates one failure point.
Now wire your receiver. Most modern setups use a single wire connection for protocols like SBUS or CRSF. Connect the signal wire to the designated UART RX pad on your flight controller, ground to ground, and the positive wire to a 5V pad if your receiver needs power from the FC. Some receivers get power from the battery through a regulator instead.
Install your FPV camera and video transmitter next. The camera typically needs 5V or battery voltage depending on the model. Connect its video output to the VTX video input, and wire the VTX power leads to your power source. Keep VTX wiring short and direct to minimize interference.
The battery always connects last. This is non-negotiable. Use an XT60 or XT30 connector soldered to your power distribution point. Before plugging in the battery for the first time, triple-check all connections with a multimeter. Verify there are no shorts between positive and negative, confirm voltage regulators are outputting correct values, and ensure motor wires aren't touching each other.
Once the battery plugs in, everything powers up simultaneously. This order protects sensitive electronics because you've verified all connections before applying power. If something goes wrong, you can quickly disconnect the battery to kill all power instantly. Never work on a powered quadcopter except when absolutely necessary for configuration.
