I also have the Mini cargo. After a crash it also started drifting, and not holding altitude. I did your suggestions for reset in the flat trim, and holding the power button for 10 sec. The props seem to be ok.
Try not fly at night,driffting is usually solved with Flat Trim,in Freeflight mini go to Start,Settings,Position ,place drone on flat surface and tap Flat Trim once or twice,that will reset all sensor. If your minidrone is still acting up you should reset drone by turning it on and then pressing and holding power button for 10 seconds
We have a new Mini Cargo Drone and it drifts badly. It never holds position and I have to give a full stick in the opposite direction to keep it close. It also doesn't maintain altitude. The first time we flew it outdoors it started climbing and did not level off (ever). It was almost dark out. Is night flying not possible?