If for some reason you can't (this I doubt as Yamaha has never let me down in this regard) get the IR DB codes to work for the OFF (you want the MAIN ID1 command and use MZOFF or Standby) do this:

Delete the IR DB command from your power off button in the mx editor.

Read my post in this link:

[Link: remotecentral.com]

Done. You're welcome. Have a good weekend everyone.