As to the power button, if the usual 4 to 10 second power off doesn't work, it's either the mainboard or PSU.
Bob
I took my computer out of storage after about a month. During this time It was stored in 3 places and not always handled by me. Anyway, today i hook it back up and try to turn it on and it doesnt work.
The light and fan of the power supply turn on, and some of the ligts on the mobo turn on, also some led lights near the power button on the front of case, but nothing else. The power button also wont work to turn the computer off after its been turned on.

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