Series 60 14l engine break switch issue

Hello everyone.i got 09 westernstar with ddec 6 series 60 14l.i changed out the engine break switch in the dash.after plugging in the new switch it blew the 5amp ENGINE FUSE and all the gauges quit working and the truck just cranks but won’t start.i try replacing it the with different switch but same issue.if i unplug the engine break switch everything works fine and truck starts.i did unplug the harness at the valve cover to see if something is shorting inside the valve cover but still same issue.anyone what could be the issue or where can i start to diagnose?thanks

 

The on/off switch cover had broken off