Hi folks,
My Mavic Air is having GPS issues. Hardware issues it seems. GPS won't connect, even though it worked fine for several flights, it now says "Cannot take off. Navigation system error, check redunancy state". This happened after a battery change. The GPS symbol is grey. I'm not exactly sure how to fix this, but I reset and reinstalled and recalibrated every part of the phone app and drone. Anyone else experience something like this? Any recommendations?

I'd refresh the AC firmware via DJI Assistant 2
DJI Assistant latest version is here https://www.dji.com/mavic-air/info#downloads

Hi there, may I have the specific firmware version of your drone? Please try to refresh the latest firmware via DJI Assistant 2 and restart the drone. If the errors persist, you might need to send the drone in. Please contact our support to start a case: http://www.dji.com/support