90 Buick Riviera doesn't like the cold?

My first used purchase, a 1990 Buick Riviera. Seller said the batter was new and I’m willing to believe him, though I did replace the connectors that were a bit loose.

As the weather here has gotten colder (0-30F), the car started occasionally stalling. The dash will say “Error” and everything dies. Normally, the car will start right back up once I stop it and turn the ignition, though. Sometimes, however, the car won’t even start. Click…click…no cranking, no nothing.

Any help appreciated. I’m hoping there’s just a loose connection somewhere, but I wouldn’t begin to know where to look.