To reflash the controller, I just need to pop out the sd card and update with the 821 software.
One question - when I popped the card into my drive , it said I must reformat it 1st - I can't open it to see what is on it now (i wanted to check that so I replace the same files..... (I'm not well versed with re flashing ...
Don't worry. If using Winbloze it does not know how to handle EXT4 formats which is why is says to format (as FAT32).
The image program does everything so does not matter what Win thinks just as long as it can see the drive.