You are doing fine with the help and on your own. The starter problem has a lot of places to inspect. The parts, the battery, the wiring, the switches and the grounds. You have a starter with a solenoid on top of it, excited by the Ignition switch. Many times these problem are a BAD BATTERY. You must start by taking it to a place that can load test it. That is your next step. Not a home test, a real battery load testing unit. Then dirty connections and clean grounds, and so on, will come next...Welcome home and thanks for your service. Banging on starters or many other components is probably not a good idea unless stranded in Zombiland.
