Wizard won't function after 20.5 (or 20.4)

After gathering dust for some months I had another go at the Wizard, previously it was stuck in a bootloop after loading a rogue patch from the site. Last attempt at updating the firmware was v20.2 via sysex, which just resulted with the flashing LED and glitch sound corresponding to LED, as some others encountered.
So now, updated to v20.5 (sysex librarian Mac, connected to “OWL-MIDI”) and the result? A steady red LED. Nothing else. Try to load a patch from the site?

CONNECTED TO: Wizard v20.5 (so the update did work?)
Program Error 0x60 Invalid SysEx

ok - fixed it, can’t delete this post!

Please explain HOW you fixed this. Helps others. Thanx.

Actually “fixed” was the wrong word. It just started working without me doing anything in particular, hence I would have preferred to delete my post, which I couldn’t immediately find a way to do, hence, it’s pointless.