To take off without the phone you need to do the "CSC" movement on the sticks, which is (unless you've changed it) pull both sticks down and inward towards the centre of the controller. That should start the motors. Then push left stick up to take off.
Not sure what you mean about Opti mode. The drone will make its own decision about what mode it is in depending on if it can get GPS lock, this is not affected by whether a phone is connected. Beware that the drone will behave very differently in Atti and Opti mode, make sure you have plenty of free space around you.
Oh... and to land without phone (which is of course fairly important to be able to do), you just fly downwards till it detects the ground and stops. Then hold the left stick down. It will slowly approach the ground then automatically stop the motors when it lands.
I think he is talking about taking of in GPS mode. The same principle applies. Wait for the green light on the Mavic. Check the telemetry and then CSC to start the rotors and take off.
Ok on another note, if u can’t connect your phone to view the live shot, using a gannet fishing release device is rendered useless in remote areas with no phone signal. If you want to use the video to look at drop zones. Am I correct?
Errrm.... you can't see the video image without a phone or tablet, that's for sure.
Just had to look up what a gannet fishing release device is.... that works down the remote radio link, you do not need a phone signal to fly the aircraft or to operate the release device. So it would be fine in a remote area with no phone signal.