Auto_Box_Update.img files are for older adapters that are on the previous firmware scheme. Once you're on v2, you need to use the U2W_Update.img files.
You're right that Carlinkit removed the U2W_Update.img for 2020-02-29. I didn't download it but I did see that it was there as of yesterday. I have to assume they pulled it because it caused some sort of problem. So probably a good thing that you didn't flash it. If you already have the previous update installed (either 2020-01-22 or 2020-02-17) then it's probably best to just wait for them to post another U2W_Update.img file.
It’s working ok on mine at the moment. I did have a mini panic this morning though. I have added a 0.3m ext lead to make it easier to take the unit out for flashing. The socket on the XC60 is tucked in the cubby next to the side wall. When I plugged in all I could get was “connect a comparable device” on the cars screen. A couple of hours later its working as expected.