Hello! I have big trouble with my OSMO ACTION ;(
After firmware update my device is broke.
When I turn it on device, i see  error appears unauthorized device with no serial number
And on my mobile phone when i try to connect i see error type: Activation failed ---- Activation data error. Please restart the device and try again.
Reboot doesn't help.
I downloaded the firmware to the SDcard. But the firmware installation does not start.
In log file OSMO_ACTION_FW_RESULT_AB.txt i see this:
[00156153]
========== 2020.07.22 19:06:16 remo-con disconnect======
[00156182]Packet: OSMO_ACTION_FW_V01.09.00.10.bin [00156191]
[00002151]
S/N my device: 129dg5x0013r92
Tell me, maybe I can somehow reset the settings to the factory settings? I do not have access to the device menu, i see only thiы error

I think you need to open a case with DJI - http://dji.com/support

DAFlys Posted at 7-23 00:24
I think you need to open a case with DJI - http://dji.com/support

Tnk. already did that. But the answer from them is not yet comforting(

Hello there Shamanin1988.  I am sorry to know that you are having this issue on your DJI Osmo Action and thank you for reaching out. With regards to this matter it would be best for you to get in touch with our DJI support team to start up a ticket at ( https://repair.dji.com/repair/index ) for the said camera and for further assistance. We have the professional team who would do their best to assists you with regards to this matter. Again, I am sorry for the trouble and thank you for your understanding.

Hello, good morning, I bought a DJI Osmo Action camera from you that arrived on September 9, 2021. The camera was used very few times and when I turned the camera on to record, it was not working anymore.  The phrase UNAUTHORIZED DEVICE WITH NO SERIAL NUMBER appears in black.  Please I would like help to get my camera working again.  I'm a customer and I paid dearly for the camera.  Thanks for the support

I have the same issue, my Cosmo action was working fine lately until I turn it on again last week. It show the same message "unauthorized device with no serial number" Last used was about months ago which work just fine. Now my Osmo turn to brick!