I have a Matrice 200 with Z30. Yesterday was my first day with it, spent the day installing apps and updating software.  Everything seemed to be working.  Today at my first flight I received the error on DJI Go 4 under Overal Status "Air Encoder Error (0x400000) Check whether gimbal is installed." Under Aircraft Status it says Gimbal Status "Gimbal Disconnected" and on the main screen is shows "no sd card".  I have swapped sd cards between the Z30 and the M200 with the same result.  The problem I have in troubleshooting is I don't know which sd card/slot is giving the error.  Is it the one on the drone or the camera? These are the 32Gb scandisk extreme cards that came with it.  I have reseated and power cycled several times and can't seem to get it to recognize the sd card.  

I've only had that message when the camera wasn't 'installed'. I'm sure you've reseated it but maybe attach it and detach it a few times.

I've only had that message when the camera wasn't 'installed'. I'm sure you've reseated it but maybe attach it and detach it a few times.

Updating the Z30 firmware resolved the issue.  The DJI assistant did not prompt me to update the z30 firmware until I actually put the file on the sd card.

We are recently procured DJI M210, Zenmuse Z30 and Zenmuse XT each two in quantity. We updated all the firmware’s and start to fly the two drones but one is working fine another Z30 would not initialize fully and the camera just sits on its side after turning on the M210. No signal from the camera and DJI Go 4 showing Aircraft Encoder Error (0x400000) image attached
Z30 Log file.

[ 25.499266]        <<<==== INTO SD CARD UPDATE CHECK MODE upgrade ====>>>
[ 25.503979]        Firmware packet number on sd card:1.
[ 25.508015]        Packet: [/mnt/usb/Z30_FW_V01.00.00.47.bin];
[ 25.513868]        New Firmware, version:1.0.0.47.
[ 25.518335]        Update mode: Normal
[ 33.522975]        [0x1 0]V1.0.58 -> V1.0.60          need upgrade
[ 35.486035]        [0x1 0] Firmware upgrade start...         
[ 42.728648]        [0x1 0] Firmware upgrade success.
[ 45.732613]        Firmware Upgrade Done.
[ 45.736540]        Result: Failed.
[ 45.740401]        Reboot the remote controller and try upgrade the firmware again.

[  5.286939]        <<<==== INTO SD CARD UPDATE CHECK MODE upgrade ====>>>
[  5.295754]        Firmware packet number on sd card:1.
[  5.300171]        Packet: [/mnt/usb/Z30_FW_V01.00.00.47.bin];
[  5.307446]        New Firmware, version:1.0.0.47.
[  5.313062]        Update mode: Normal
[ 13.321204]        [0x1 0]V1.0.60 -> V1.0.60          not need upgrade
[ 13.325390]        Check Firmware Done.
[ 13.329706]        Check Result: Error.
[ 13.333940]        Failed to obatin firmware version. Power cycle the drone to upgrade the firmware again.

If you move the z30 to your other M210 does the error follow?