After several months of not using drone, my friend today turn it on and he went for an upgrade.
But then problem pop-up. Whenever app starts to upload firmware to drone, this weird ...@-@... characters are displayed and app goes to step where drone needs to be connected to remote/app.
So this way he can't upgrade. It keeps looping this way.
Check image here

He uninstalled app on the smartphone and installed it again, but the problem remains.
Any thoughts what is happening here and how to fix this ?
But then problem pop-up. Whenever app starts to upload firmware to drone, this weird ...@-@... characters are displayed and app goes to step where drone needs to be connected to remote/app.
So this way he can't upgrade. It keeps looping this way.
Check image here

He uninstalled app on the smartphone and installed it again, but the problem remains.
Any thoughts what is happening here and how to fix this ?