If multiple power on codes are available for Sony BD devices, have you tried them all? I think "eject" also often works as a power on, which MAY be what you're actually using here (to test, if sending it opens the tray while its already on, I'd suspect it's "eject", but if it doesn't, and it only does anything when it's off, then I'd say it's an operational quirk of that unit - make sure you have the latest firmware).