Yamaha HTR-5640 AV-Receiver turns on for a few seconds then turns off?

I have a Yamaha HTR-5640 AV-Receiver for my speaker system, and I have not used it for a while. Today I plugged it in, turned it on, and it stayed on for a few seconds then turned off. Now, whenever i turn it on, it turns off after about a second. I opened it up and checked, and the fuses were fine. What should I do?
Update: Everything, except the power, is unplugged from the system and it still does not work.
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