Have you checked the two fuses in the back right hand corner? They sometimes blow just because they’re a bit tired, but if one has blown and when replaced blows again, then most likely the output transistors are short circuit. They aren’t expensive and if you know someone who knows about these things it’s a pretty straightforward job. It’s a nice amp, but there’s loads of them around so you might be better off returning it and looking for one that works.
Time flies like an arrow.
Fruit flies like a banana.