2015 Freightliner Cascadia - Intermittent No Start - No Crank - CPC or MCM?

Having a nightmare with this 2015 Cascadia. Randomly it just won't crank. Dash lights up like a Christmas tree and the gear indicator shows a dash or a 'N'. When it happens, I lose communication with the MCM. If I let it sit for an hour or wiggle the wires at the firewall, it usually starts right up. I've checked the batteries, they are 6 months old and load test fine. I cleaned the battery terminals and the ground studs on the frame. I'm worried it's a CPC unit failing because I heard these were common for that year.