Hello everyone, i found my old tello, and battaries are charged, but when i pout em in they blink red? idk if ur gonna read this, so for more info jsut comment

Very frustrating!

I've a very similar problem.
Power on, a green light is seen, then 3 or 4 red blinks and nothing else happens.
Connecting the usb power cable seems to do nothing, not even charging the battery.

I finally solved my problem by upgrading the firmware. The procedure (which I had to repeat a few times until it worked) is as follows:

* Without the battery, press and hold the power button, then connect the charger.
* Continue holding the power button and insert the battery.
* When the green LED turns off, release the power button.
* After this, a red LED should remain lit.
* Connect your device via Wi-Fi to the Tello and start the tello app. It has to show connection to the dron now.
* Proceed to install/update the firmware from the app. Even if the firmware progress seems to get stuck, wait for a few minutes (less than 5 minutes). As long as the red LED remains on, the process is still ongoing.

I did this with my iPhone, using version 1.6.6