Using the remote I can no longer change dvd channels nor as I mentioned before "Mark" for any purpose at all. Yes the batteries are fine since I've changed them for new ones just in case and the other functions like Enter, Setup etc work fine with it. I've unplugged it from the mains and reloaded the system hoping it might work, pressed standby as per manual, aiming like I used to when it was working, but to no avail. What next?