2015 Dodge Grand Caravan Starting Issue

I have a 2015 Dodge Grand Caravan. When you turn the key in the ignition
the car just makes a click click click click. Eventually the car starts up, but
usually dies within 2 seconds. Then when you try and start it again, it starts
up, doesn't die, and the interior lights get noticeably brighter when what I
assume is the alternator taking over power gen. every time (has been
happening for a week or so). I shorted the starter relay contacts and the
starter seems to crank normally, so I dont think its a starter. Switched the
starter relay with a known good and same problem happens so its not the
relay. Used different keys, so definitely not the key. Started the car in park
and neutral, same problem on both. Anyone have any ideas what could be
causing this?

If the battery were causing it I would think it would just click once, no power
etc. Has anyone heard of any internal problems with a battery (ie cells
shorting etc.) that could cause this?

Any input is appreciated. Thanks