YEAHHHHH, thanks for the suggestion, works also for me and finally fixed this mess!!!
Just to summarize:
- delete the original
Tello App from your phone
- download the 1.1.1 version (link here
Download Tello 1.1.1 Android APK) straight on your mobile device
- install the App just by opening the downloaded APK file and then open the App
- download through the App the latest firmware
- with a full charged battery, turn on the
Tello drone in "reset mode" (keep pressed the power-on button until green led stays on, then when the light turns off release the power button: now the led keeps blinking red and you can connect to the drone's wifi)
- connect the drone to the App and install the new firmware on it (now you will not receive the "less than 50% battery" error!!!!!!!)
- the drone is now correctly working again, so you can also delete the V1.1.1 App and install the latest one from the App store
ENJOY