I realize most of this thread is old. I just bought a used Helix Rack. It was on a very old firmware -- I think 1.0.65. I upgraded to 2.92, which presented problems of their own. Having worked through it, I had used the Rack for several days without issue. I left it on overnight, and it had dropped connection to the computer. When I rebooted, it had the -28 error in the upper lefthand of the screen. I tried rebooting. I tried all the reset modes, but only Update Mode worked. I was able to downgrade and upgrade fine, but every reboot had the error (went down to 1.9 and 2.8, and 2.90 and 2.91 and back to 2.92, and probably a couple of others). I called Line 6, and they tried running through some of the resets without luck.
They finally opened an RMA and I am told replaced the DSP board. Glad it's repaired, back and working again.
