when finished flying my remote won’t shut off it stays in connecting mode

Double tap the power button on the Remote then hold it on second tap for 5 seconds it should power off..  

I am sorry that you are having an issue in shutting the remote controller of your Mavic Pro. Please try these process to turn off the remote controller. Please press the remote controller's power button once then release then press and hold for 3 seconds then release. This process should turn off the remote control.