HELP "Failed to enter command mode" error

I just bought the 3DR 433Mhz radio telemetry kit from DIYDrones..


The two boards of the 433Mhz looks same. After I received the kit I soldered the header pins to the boards and connected to the FTDI cable.


Now one board connects fine to the configuration tool and I am able to LOAD SETTINGS from it..

and the GREEN LED is blinking..


But when I am connecting the other board to the FTDI cable the GREEN LED is solid and RED LED is blinking every 1 second.

Even I am unable to LOAD SETTINGS from the board..
 When I click on the LOAD SETTINGS it shows "Failed to enter command mode"


I tried uploading the firmware but it failed..

So I tried in force boot by connecting the GND and CTS and connected the FTDI. The RED LED was solid and then I was able to upload the firmware.

But still after uploading firmware also it has same problem. The GREEN LED is solid and I am unable to connect.



Here is a video on Youtube to show how it is reacting..

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  • Any updates on what the cause was or how to fix it? Did 3dr replace your radio? I have the same problem with my "Air" Module.

    • So I have been in touch with 3dr and troubleshooted with them, and the result is mine could not be saved. It is unable to communicate with the computer so the firmware has been corrupted. Its a bit annoying as they dont offer a repair service so I have to buy a new unit.

      Good news is the new version 2 modules are compatible with the older version 1 modules.

      • I have tried jumping the CTS and GND together, and was able to force it into boot loader and update the firmware.

        I powered down, removed the jumper and powered up again and I still get the "Failed to enter command mode".

        Sigh. Just another bricked unit I guess. I do wonder how it happened?! So I don't do it again!

        I will have to order another module to replace the bricked one if I want to use 915MHz.

        I have a 433MHz set which is V.2 and working fine.

        • Show printscreen from config tool.

          • Try to inspect board carefuly and eventually resolder - IMHO you have nothing to loose :-)

          • It seems there may be a crack in the board - by squeezing the board between my fingers I can get it to work, and I even forced it into bootloader once! Well the red light stayed solid anyway just like it does in bootloader mode. Might have to rework the solder...?

            But it seems it is definitely NOT BRICKED! :)

          • And now its working again. Weird.

            Will have to try powering up without the ftdi cable but I can see it in Mission Planner now and it has survived several power downs and restarts now.

            Fingers crossed! Thanks again Marcin!

            I think the trick is to force it to bootload, update firmware, power down, remove jumper and then power up again.

            mission planner success.JPG

          • I tried to open it in Mission Planner but it had the solid green light of doom and while I can force it to bootload its not happy again. This is so weird!

            It was working! Drat!

          • But now it doesnt work... ? I don't understand - it was working and now its not again?

            It Works!.JPG

          • :-)

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