What troubleshooting have you done to verify that the amp is not working?
What would be useful is a detailed description of the symptom. Things like;
1.Do the radio functions show up on the LCD display?
2.Do the headset speakers work?
3.If the display works, when you operate any of the buttons, does the display indicate that the functions are changing?
4.When you say the amp is not working, does that mean you have no audio through the external speakers?