Help needed please. Mac mini doesn't power up

After dinner I wanted to wake it up but couldn't.
Bern wrote on :

Hi,

This I bought an APC usb 2.0 hub, plugged it in in the mini usb port and inserted 2 usb printers, 1 external hd and a wireless keyboard and mouse in the hub. Everything worked fine and instead of shutting down the Mac mini I used the sleep mode. After dinner I wanted to wake it up but couldn't. I tried to force shut it by holding the power button for 10 seconds but nothing happened. I removed the power supply adapter and noticed that therre still seemed to be some current as the sleep mode light continued flasing for another 20 seconds. Once it was off I let it stand for over a minute and then reconnected the power supply and pressed the power button but nothing happens. Unfortunately the warranty expired 2 months ago.

I would appreciate it if anyone has an idea as to what could have happened.

Thanks a lot,

Bernard