iMac Bondi 1998 won't turn on

[viksn0w]

Ok, yesterday worked fine, but now I wanted to set it up for an old fashioned Internet Browsing and I press the power button and nothing. The iMac seems almost dead, but there is still the "bzz" noise that comes from it. Someone knows how to fix it?

[viksn0w]

Now I found out that when I click the power button, this sound changes to a lower frequency