Purchased gen4 in November 2024, from a dealership. 12 volt battery is said to be new (I am not seeing a date anywhere on the battery.) I also carry a booster. No signs of trouble, yet car is dead when I get back in the car at the grocery store. Booster does not appear to be helping. Not a single dash light. Maybe some type of system reboot?
You need to take a DVM reading; before poking around in the dark. Your booster doesn't work, because it's not reading any power - so it won't turn-on unless you bypass the safeties and force it ON. Loose battery connection, when they swapped out the battery? There's also that little fuse block do-hicky on the positive cable.
Think you were spot on. Terminal connections were tight, but there was a loose bolt about 6" back on the negative terminal. Once that was tightened, car was good as new. Strange how I had been driving the car daily for months including a long road trip and no signs of power problems. One thing I am sure thankful of is that the battery is under the hood, not burried in the depths of the cargo bay like our previous gen 3s,... much easier.
