Disconnect the cable.
Pull the four corner key caps.
Pull the G and H key caps.
Remove all 5 screws, all 5 are the same.
Twist the chassis so you can grab the circuit board at the lower right corner, it's easiest here.
Lift from the bottom and as soon as the circuit board clears the front edge, slide the board forward to release the usb connector.
It may be a bit stiff on the last part as some have found the hole for the usb connector to be a tight fit. I used a small file to open mine up a teeny bit so it needed less effort next time.