If you disconnect a) interconnects and b)speaker cables an try to power up does it goes on OK?
If no external connections exist and the amp powers OK then you might have a short circuit most probably in the speaker cables. If it does not then you indeed have a problem with the amp
If no external connections exist and the amp powers OK then you might have a short circuit most probably in the speaker cables. If it does not then you indeed have a problem with the amp