Do you have another computer to try it on, might seem like an odd suggestion and probably a long shot, but a long while ago when I first started to use Axo, I was running the patcher on two different versions of OSX, and couldn't connect at all on my music machine, and went through all of the suggestions for pressing S2 and putting it into DFU mode, the issue was solved when I used my day to day computer with a different os and managed to get it into DFU mode, then I did a clean install on the mac that wouldn't connect.....
Like I say a long shot also (I'm sure you may have already done this) different usb cable, the micro usb is fraught with connection problems, I use a magnetic cable now so that I'm not constantly plugging and unplugging the micro usb connector