same issue here, with 2 separate units. Boot failure Res=28, DSP Init. It will occasionally boot, but I typically have to cycle the power multiple times, like i'm playing a slot machine. Not so cool when you're setting up to play a show.
Returned the first one and exchanged for the current one, having same problem. Just submitted a ticket, but honestly wishing I could just get a refund at this point. Not inspiring confidence seeing all of these instances of the same problem from others!