Yeelight Smart Bulb V2 problem after firmware update

Yesterday yeelight app showed me that there is one firmware update available.
I chose to update but updating seemed to stuck (for 30min), so i closed the app.
After that the device could not connect.
I tried reseting the lamp many times, uninstalled and reinstalled the app, set DNS to, reseting the router, turn WPS on and off.
Each time i reset the lamp (many colors are flashing then is set to white), the app can connect to the lamp , but then lamp fail to connect to the network (flash once in white color) but then i get timeout error.
I think it is the firmware that caused this problem.
Is there any possible way to revert the firmware update?
Is there any solution to this?
MI ID: 6206048343