I've done the bypass mod and it works... BUT it does not work when I plug the GPS antenna in. Any ideas on why this is? Loose connection... etc?

I just tested it again and pull the antenna out and drove around watching videos and it worked. Plug it back it back in and I get the warning.

The bypass is not done correctly. Check your connections

Check to make sure the mute wire relocation/grounding is correct and solid. It works without the GPS antenna in because it's not getting any info to let it know the car is moving. Once the antenna is plugged in it realizes the car is in motion and locks you out. Moving the mute wire bypasses that.