Just picked up a 'used' floor unit as an upgrade to my LT... same issue. I think the unit was on v2.3 - already had HX Edit 3.0 installed so did a backup of the floor and went for it - 'update failed - entered update mode'. HX Edit wouldn't detect the Helix any more o I tied rolling back Edit to 2.81 then 2.82 with no joy.
As above, opened the old 'Updater' I still had installed and 3.0 installed without any issues :-)