Hello, my Tello won't switch on at all. Tried 2 different batteries, both fully charged. Tried plugging USB directly in. Tried holding down the button while inserting the battery. Absolutely dead - no light or anything. Any ideas?
Many thanks!

Incidentally, it was working fine when last switched off - no catastrophic crash or anything.

Dear customer,
If you can see the blue indicator light when the battery charge through the aircraft, it means the battery has been fully charged. Please press and hold the button for more than 6 seconds until the green LED lights off and the red LED continues to breathe. Connect the mobile phone to the aircraft's Wi-Fi to upgrade the firmware. If the light still doesn't light up, please take a video showing the issue and send it to us via support@ryzerobotics.com. Thanks a lot.