Will be very surprised if dirt/corrosion is the problem. The cables/posts look brand new almost. (This model has a cover over the battery so it's been well-protected). I have not inspected the inside of the brackets that connect the cables to the posts but will next chance I have but again, there's zero corrosion, etc. on the posts or anywhere else that I've seen in my multiple disconnection/reconnections of the cables. Also getting some odd other things happening---after turning the ignition key 3 times in an attempt to start the car the trunk started popping itself open! Did this twice. It's also begun giving me 2 short horn beeps after hitting the remote lock on the key as if a door is open on it after I've confirmed they're completely shut. Starting to think this is some weird electrical/software problem. Probably towing to the shop/dealer tomorrow.