Hi. If you haven't already, disconnect all of the speaker wires from the amp and then see if it stays on. If so, it's either the wires, the speakers, or the connections. Try connecting one speaker at a time and see if you can narrow it down to which set of hardware is causing the amp to shut down. Once you do that, you can swap speaker wires and speakers to narrow it down even further.
If you create a short circuit between a "+" and "-" speaker terminal, the amp will shut down and go into protection mode. So, if it says on with nothing connected and shuts off with something connected, carefully check your connections and make sure there aren't any wire strands bridging the gap between the terminals.