engine starting problem

Help, I have a 2003 SeaRay Sundander 280, My port engine clicks when I try to start it. The only way it starts is by jumping it from the backup battery. I changed the battery and still same problem. Maybe I changed the wrong battery? I looked it up on schematic in manual. Any suggestions?

I have a 2002 310DA with 350 mag mpi v drives. Boat has been idle for 3 months. Turn on ignition and no warning horn sounds. Also no audible fuel pump pressure up. Engine cranks won't start. Same situation for both engines. Turn starboard ignition on and the auto fire extinguisher light goes on...