u61?

I am getting an error code U61 on the LED screen and on the TV display the resolution suggestion is to press enter, which will close the disc drawer, and turn the unit off; then power back up. I have done this but the unit went back to a U61 error initially with the same error message on the TV screen but the LED screen just says HELLO. Tried the sequence again but it's just goes back on the same loop. There is no disc in the machine.