My 300 is doing the same thing. I did my checks and found the starter is bad. Do not buy parts until you identify what is bad. First, you have to start with a good fully charged battery. The click that you hear is the starter relay that is next to the battery. Do a voltage test on the battery. It should be around 12V depending on condition. Connect a volt meter to the starter electrical terminal. Now turn ignition on and hit the starter switch. If the relay is good, you will read battery voltage at the starter terminal. This means your starter is the problem. If you do not read battery voltage at the starter terminal, the problem is the relay or maybe a wiring problem. A couple of more tests will help determine which.
Doing the direct feed to the starter as suggested will be a true test. Again all this requires a good battery. If you suspect the battery you can do the direct test using battery jumper cables and your car or truck battery.
