Determine what is not working on start up, and replace appropriate module. I'm not sure how to test the modules with a meter, you would need a wiring diagram of the module and test it with live voltage to open relays/provide proper current draw. What I do when troubleshooting these systems, Is put a meter on each component and check for hot and neutral going to each component. If you are getting like ~20 volts on the neutral it is a module.