Motors will not arm. I replaced one motor that was smoking after hard crash on takeoff.

Also keep getting compass error - magnetic interfierence.

Will motors start if compass is not calibrated?

Hi there. Thank you for reaching out and we're sorry for the unpleasant experience. In this kind of situation, I'm afraid that you may consider sending the unit in for a proper diagnosis. You can contact our support team to start up a ticket at https://www.dji.com/support. Thank you for your understanding and support.

All sorts of possibilities here. If one motor was "smoking" it is probable that the ESC is also damaged. Sounds like quite a heavy crash so you need to get it checked out by an expert.

No idea where you are but in the UK I would contact Andrew at Droneoptix.