2013 Dodge Mega Cab 3500. New batteries, lights are flickering and it won't turn over. Dome light flashes three times. Seems to take a charge but won't start, just clicks.

 

Bad grounds. Make sure your battery connections are clean, and tight.

 

Alternator?

 

the connections to the battery terminals themselves were pretty clean. I did clean them anyway before installing the new battery. How do i find/check bad grounds?

 

2013 is definitely not a 3rd gen lol

 

I've not worked on your particular year but generally, you trace the cables back to the engine block and frame. The ends at the frame tend to rust but never get checked. There may also be one or two small grounds going from the firewall to the engine as well as a small cable from the body to the battery.