As long as you're waiting, go through this list anyway:
How to calibrate DJI Mavic Mini IMU?
Step 1: To calibrate the DJI Mavic Mini, first place it on a flat surface.
Step 2: Power on the DJI Mavic Mini.
Step 3: Open the DJI Fly app and connect to the Mavic Mini.
Step 4: Enter in the General Settings of the DJI Fly app (3 dots).
Step 5: Open the Main Controller settings (quadcopter icon).
Step 6: Scroll down and click on "Sensors".
Step 7: Click on "Calibrate IMU".
Step 8: Click on "Start".
Step 9: Next, you will see "Calibrating, please wait".
Step 10: Place the Mavic Mini in the various positions shown on screen.
Step 11: When lights change from blue to green, then you are shown the next position to put the Mavic Mini in.
Step 12: Stand the DJI Mavic Mini on it's side with the front facing right, check for the green calibration light.
Step 13: Then stand the DJI Mavic Mini on it's side with the front facing left, check for light to turn green.
Step 14: Stand the Mavic Mini on it's nose (camera facing down) and wait for green calibration light.
Step 15: Next, stand the Mavic Mini with it's back end facing down and watch for the green calibration light.
Step 16: The last DJI Mavic Mini calibration position is to place the Mini upside down on the flat surface and wait for green light.
Step 17: This completes the DJI Mavic Mini Calibration with the message stating "IMU calibration complete. Please restart your aircraft".
Step 18: Click OK and restart the Mini.
What if DJI Mavic Mini IMU calibration failed?
● Check that the surface where you are doing the calibration is totally flat.
● Try the Mini IMU calibration a second time.
● Do a compass calibration.
● Update the Mini firmware, if there is a new one available.
● Allow the Mini battery to fully discharge or remove the battery from the Mavic Mini.
● Allow the quadcopter battery to fully discharge or remove the battery
● Wait a couple of minutes. Then charge your battery fully in the Mavic Mini and try the calibration again.
● Re-install the DJI FLY app just in case this issue is with the app not sending correct data to the Mavic Mini.
● If the IMU is still not calibrated, then contact DJI or the retail outlet or store where you purchased the Mavic Mini.
Taken from GearBest web site