The RCM is inside the box by the battery, the module closest to the engine.
However, having said that, I don't think the RCM fits your symptoms.
Do this : If you don't already have a cheap digital meter, buy one and see what the battery measures across the 2 posts.
Should be 12.2 volts or better.
If it is, then start it up ( if it will ) and measure again. Should be 13.8 - 14.2 volts.
Now measure from the positive terminal to a good place on the engine, should not vary very much from the 13.8 to 14.2.
Report back.