I had the IMU problem on my Mavic Air and tried the “slap on the back” technique a few times then decided to open it up and reseat the IMU but neither of these worked.
Having become confident at taking the drone apart and reassembling it I decided to search for a replacement IMU but they are hard to come by at a reasonable price for the original Mavic Air and are all labelled as “refurbished” which puts me off. I saw this post and I thought it was worth a try with the Mavic Air 2 IMU. I can confirm that the ribbon cable physically fits, although the plastic casing is a different shape (I planned to try and fit it into the original). However, I get a “disconnected” error now. I’m not sure if that confirms that the Air 2 IMU is incompatible, or there is another issue. I would be interested to know if anyone else has tried this.
After the Air 2 IMU didn’t work for me, I ended up buying a refurbished Air 1 IMU and that solved the problem. I think that confirms that the Air 2 IMU is incompatible unfortunately.