CM500 Cable Modem Downstream Constantly Flashing Green

Your logs are indicating line issues. 

do you have a screen snip of the cable connections page? 

Check for splitters, signal attenuators, and amplifiers in line. Remove them if you do. 

check the line for kinks, damage, old/loose/bad/corroded connections and replace them if needed. 

I'd move the modem to right where the coax enters the home and connect it there.