1996 Stratos 201XL & Clarion Marine XMD3 Radio HookUp

[Dealgirl19]

We just purchased a 1996 Stratos 201XL and it has a Clarion Marine XMD3 Radio in it but we can't get it to work. The red wire is ran to the Accessory switch but the black wire isn't connected to anything. I'm not sure what the best way to test the radio and make sure it even works out be? I wonder if the accessory switch maybe doesn't work either?? We tried connecting the black (ground) wire to metal on the boat and trying but still got nada.... Advice??

Thanks in advance!