I'm having trouble upgrading my slave remote. The controller doesn't beep or turn blue like the master remote did. Am I missing something here? Do I have to have the remote in master mode to upgrade?

No, but you do need to delete the TXT file from the SD/USB before doing the second upgrade.

Put the SD/USB back into the computer, delete the .TXT file (read it first and make sure it says SUCCESS) and then try again.

I had some trouble as well at first.  This fixed it...  I reformatted the sd card and reloaded the firmware on it.  Then I used an sd card reader connected to the remote via USB and boom, 1000 annoying beeps later, new firmware installed.  Hope that helps

Had the same issue: Deleted TXT file on the SD card. connected USB cable between camera and Slave controller. Booted controller and Drone. Within 60 seconds the purple led on controller swithed to Blue: Then the controller beeped D-D-D-D, D-D-D-D etc It finished when the LED went green.  Stopped the slave controler and drone, removed the SD card. Rebooted the Master, Slave and Drone and both Tablets said they were connected with a controller with the right firmware. (until then the tablet on the master said "normal" and the tablet on the slave said "update required") . Will purchase an SD-USB reader, which will  probably make this process a lot easier.

Having the same problem with my slave remote. I think in my case the USB port of the remote has stopped working. I updated the drone with no problems using the SD card in the camera. Then I updated the Master controller with s USB stick. Again no problems. Then I went to do the Slave. Plugged the USB stick in (after deleting the txt file), and....nothing. The light is red, beeps twice and turns steady purple. It sits there for a few minutes then starts beeping continuously (lights stay purple). So I tried plugging the slave into the usb port on the Drone camera and following the directions in the video on the website. It looked like something was happening, however when all said and done I checked the txt file and it said the firmware was the same or older than that on the drone. It was like it did not even recognize the slave controller was plugged in.

So further testing I plugged the Ipad into the Master controller and started everything up. Ipad asks if you trust this computer, DJI Pilot app shows connected, and the Ipad shows it is charging. When I plug it into the slave, no request to trust this computer, App shows disconnected and it does not show charging. Repeated the same using different cable and my Iphone 6 and got the same results.

Anyone have anything else I could try or does this look pretty much like a faulty USB port?

RPM aerial Posted at 2015-4-27 11:50
Having the same problem with my slave remote. I think in my case the USB port of the remote has stop ...

It does sound suspiciously like a bad port.

RPM aerial Posted at 2015-4-27 11:50
Having the same problem with my slave remote. I think in my case the USB port of the remote has stop ...

That sounds very much like my experience, although the update started on the second remote but never finished. Now it behaves like yours. Long beep on start up, red light then purple and is ignored by the iPad or gimbal. It looks like it is no longer communicating with the USB port but it is a logical thing and not a physical. It is too much of a coincidence that they dropped out just as we were updating firmware. Anyway, mine has gone back to DJI but I have not heard anything back from them.

Mine is brand new, just unpacked from the box on the weekend. Has not even seen a fight yet and already slave controller is dead in the water! I am discussing with my Supplier who is the Tier 1 support in Canada...whatever Tier 1 support means with DJI. I am hoping they will exchange it and they can deal with DJI. That is one of the reasons I bought from them so I would have local support.
I guess I will wait and see....

I have found that if the firmware on the controller is several versions old, you have to bring it up to a more current one. I just bought another controller to use as a slave (new in box) and it was of a version of software/firmware that it wouldn't update until I put one in that was 4 versions old. Once I updated that and 3 versions old (using usb) it then let me update through the app. Just FYI.

Not sure if it makes a difference, but I always put mine into master mode for the upgrade and then put it back to slave after its done....