Just did this update on my controller. Pretty cool process, it recognized the controller didnt have enough battery to continue and denied the update. After it charged for a bit, it was all pretty straight forward. Now to find the other controllers I got around the house and get them done. Had to use Chrome to do all the updating though.
Maybe this is better than downloading a one-off utility from a manufacturer's slow FTP and selecting a firmware file in its file picker and hoping that the combination of flashing utility version + firmware image + my hardware + my OS + the current stellar constellation aligns, and I will still have a working device after this ceremony.