Strange starter issue

Hey guys,
Recently changed my starter(less than 3 months ago). Yesterday morning I tried to start my car but once I turned the key to the start position the power on my dash went out as well as no cranking. Bought a new battery, Checked connections with multimeter, my half assed search for bad grounds didn't find anything. Gave up and today I went back and checked the starter cables, still tight. Wacked the starter and then the car started up fine.
I'm not convinced the starter was the root problem, or was it? What areas should I check again?

Bad starter, warranty time

If it is an automatic, try the shift sensor that prevents your car from starting if it is not fully in park or neutral. Try starting in neutral or wiggling your shifter to see if it starts. Good luck