Hi Jim, I recommend making sure you exactly copied the client_id, client_secret and pin_code into openhab.cfg. Also make sure that there are no leading or trailing whitespace characters on any lines in openhab.cfg.
If you have verified all of that, then try the step to generate a new pin_code and paste that in place of the previous pin_code value in openhab.cfg, stop and restart openHAB. The binding will get try to get a new access token if it sees that you changed the PIN.