I'm sorry to hear that you're having this issue. Turning off the unit is not recommended, but may be the last resort.
What I suggest is holding down the FF>> Button for 15 seconds to see if it resets. If not, try pressing the STOP Button. If it still doesn't respond, you may have to unplug the unit.
If you can, before you do, try to empty the disc tray.
Plug the unit back in, power it on, and press the FF>> Button down on the unit until it cycles. It should prompt you for a language selection (but may quickly flash off), and you should be able to access the menu.
I downloaded the Firmware CD 2.8 upgrade and burned the ISO straight on to a disc. I put it in the player for the upgrade and it verified it but never prompted me if I wanted to proceed Yes/No, it just went right to Now Processing and do not shut off and has been stuck there for several hours. What are your suggestions?