What to do when the SpeedyBee F405 V3 flight controller can't be powered by the ESC?

If your F405 V3 flight controller works properly, when you power your quad, the flight controller's PWR LED(red) will be constantly on, and the FC LED(blue) should blink several times and will blink from time to time after then.

But if you plug a battery into your quad but the SpeedyBee F405 V3 flight controller only shows a red LED or even has no LED lighting up,  please follow the steps below to troubleshoot.

Step 1. Check if the flight controller is bricked

If you power the flight controller with a USB-C cable but it still only shows a red LED:

It's probably bricked. You may refer to this article to bring it back in DFU mode:

How to flash firmware for a bricked flight controller?

But if you power the flight controller with a USB-C cable and it can boot up normally(The green LED blinks once and the blue LED blinks several times) and connect to the SpeedyBee without any issue, it probably indicates a bad connection between the ESC and the FC, or the power chip of the flight controller is burned out. In this case, go to Step 2.

Step 2. Check the connection between the ESC and the FC

After connecting the flight controller and ESC with the 8-pin cable, power on the quad. Use a multimeter to measure the voltage between the BAT pad and the G pad as shown below(It should be equal to the battery voltage):

If the voltage reads the battery voltage, it means that the power chip of the flight controller is probably burned out. This condition is generally caused by surges (over 30V). Please send up-close and in-focus photos of both sides of the flight controller to [e-mail]. Please also send us your purchase screenshots including the purchase date.

If it reads 0V, that means the 8-pin cable or the FC 8-pin plug, or the ESC 8-pin plug is damaged. Please unplug the 8-pin cable between the ESC and the FC, and solder two wires between them instead: