I have seen many posts here and wasn't able to comment with the solution but after buying 3 or 4 different KM717 Dell Premium keyboard from Dell and Amazon, I was extremely frustrated having spent so much money.
I finally found the answer online and thought I'd share:
Turn off keyboard.
Keep Esc+’ (Esc + apostrophe key pressed) and turn on keyboard.
Alternative: For those interested, these keyboards enter DFU mode with ESC+F1 held during power on. LED light goes orange and keyboard advertises itself as DfuTarg to bluetooth for flashing.
