I just had the same issue with my new iPad Pro. You're going to end up losing your 2.4.3 version. You'll need to place the Mini in recovery mode. Turn off your iPad and hold down the home button as you plug it in to iTunes on your Mac or PC. You can let go once you see the iTunes connection appear on your screen. From there you can completely wipe the iPad and restore to factory settings. Upon completion, you'll need to set up the iPad as new and not restore it from a prior backup. I had to go through this for days before it was figured out. I was also on 2.4.3 however, I think this is the only was to fix you issue. PM me with more questions.