Why is there no display?

Hello, I am sorry about your issue. Considering the age of the receiver [2005] it might be difficult to find parts for a repair. Please contact us at 800-229-1687 option #3 so that we can discuss possible options. Thank you, Onkyo USA

Go to breaker panel,turn off and wait a minute and turn on,may reset it.

If you have tried using different input devices, looked for loose contacts
in power outlet, RC Jack, cable and connectors, the TV might need service.

I had the same problem some time ago with another machine. It sounds as though the safety locking system has stuck on.
It should unlock between 1 to 3 minutes normally.
I had to turn the power button off and on again to get it to open.
It did start working again itself after a while.

I have the exact same issue, except that it sometimes turns on (very rarely though)

There isa problem in CRT Board.Loose connection problem in vertical section.Need for resolder the board.

How long does it stay off? 30 to 60 minutes?? Sounds like the cooling fan is not working or air vents on the unit are blocked.... I saw one unit years ago with this complaint that when the customer turned on the MWO, the fan came on and pulled a curtain covering the pantry up to it, blocking the air flow and causing it to overheat and shut off....

Have you check the power supply,that's what it seems to me.

Might me a bad oven temp. Sensor.

Your power supply is going south, I have an old sony with the same problem. The voltage level drops and does not have enough 'kick' to start. It will work better when it is warm. The module will need to be replaced.