Push the MENU button on your remote twice. That's the System Info screen. A few lines down is the current software version. It will start with an "L" on your 622 and is most likely L4.48 or L4.49 at the moment.
Without having the screen in front of me, I can't remember enough details about the rest....
Without having the screen in front of me, I can't remember enough details about the rest....