That didn't really change anything. The only thing that did work besides repeatedly turning the car on and off with the engine off was to lock and unlock the car from the fob with the fob held on top of the steering column.Try to repeat the process. Open and close again the FOB. The battery is probably not touching enough the metal contact giving less voltage but enough to work. If this doesn't work, you can unplug the battery terminal on your vehicule for few minutes. Somebody mentionned that it worked.
It does however demonstrate a false positive message for a battery failure when there is nothing wrong with the connection or the battery itself.