@Vitiky 

Hi, 
Usually, you can refer to the following instructions to troubleshoot when you fail to upgrade the firmware.
What should I do if I failed to update my Deco?
 

Please confirm the following information if the same phenomenon persists.
  1. Please refer to the instructions below to find the hardware version of your Deco, and confirm it's EU, US, or another version on the Deco's bottom label.
      How to Find the Hardware Version on Your TP-Link Device
  2. In the Deco app > More > System > Update Deco page, please check the firmware version of your Deco and send it to us.
  3. Do you update your Deco's firmware via the Deco app or its web UI? If you update the firmware via its web UI, where did you download the new firmware, and what's the firmware version?

Best Regards