When push the power button, I can hear a relay

When the unit functions correctly, you should hear 2 clicks. The first is the power relay that "starts" the unit. The second is the speaker protection relay that will kick in the speaker connection. If you do not hear the second click, the unit is in protect mode. This means that a problem was detected in the amp section and the unit is prevented from connecting the speakers. This is done to prevent further damage. Typically the output transistors fail and cause this. Expect a parts cost in the $25-$50 range for this repair.

Dan