Brian, yes, the BIOS/UEFI updater did not ask for a restart. It seemingly did nothing, just went away.

Now I re-mapped Left Shift to Insert and it works just beautifully as an NVDA modifyer key. AS I said, not convenient at all, but maybe I can live with it. Fortunately, I don't need to make the final decision whether I want to return the computer or not before in around three weeks.