I don't get any front display or any sound when turned on.

Do you hear any clicks? If not, the standby transformer or related circuitry is bad. If you hear 1 relay click...the audio output section is most likely the problem. The first click you hear is the main power relay...and should see display.. the second relay click is the protection circuit relay engaging to let audio to your speakers...if the second click is not heard (it should occur in 3 to 5 seconds) there are shorted output transistors or a shorted output IC trying to blow your speakers with 50 to 75 volts dc. The protection circuit monitors the speaker lines for voltage. They should always read milli-volts only...not even 1 volt.Anyway, good luck