I am a newbie flying any drone, let alone my DJI Mini 3 Pro.

My aircraft doesn't take off anymore. The forward and backward vision sensors in the DJI Fly app are red and mentions both sensors are unavailable.

What can I do to resolve this problem?

You could try downloading DJI Assistant 2 software and then perform a vision sensor calibration and see if that will resolve the issue.

https://www.dji.com/downloads/so ... sumer-drones-series

Problem solved

you just need to take off)

Hi there. Thank you for reaching out. We're glad that you have managed to isolate the issue that you experienced. Please note that the aircraft will disable vision sensors when it is on the ground to reduce power consumption. When the aircraft takes off, all vision sensors will be enabled. Please feel free to use them. We appreciate your valued support. Happy flying!