Mystery Jump

I was out scraping the ice/snow crusty mix off my driveway today when I heard Geoff trying to start his daughter's Ford minivan. It was plenty cold this afternoon, like 2°. It had previously been in the garage for a few days so we could figure out which door was causing the dome light to stay on. It was the sliding door. It has 4 contacts, 2 of which were quite dirty/greasy. I got out my can of Foamy White tuner shower from the mid '80s to help clean the crud off. He also took some very fine sandpaper to both sides. That fixed it. So later, he parked it outside. Then today it wouldn't start. It had plenty of battery, as it was cranking just fine. It just wouldn't light. We tried letting it sit, holding the pedal to the floor (I don't remember if that's a trick to get fuel injected engines to "choke"), etc. Finally, he wanted to try jumping it. I thought it was getting plenty of juice, but thought what the hell. Either that did the trick or the engine was finally ready to ignite. So what do y'all think? Could extra juice cause the electronic ignition to fire hotter? Or the injectors to squirt harder and make a more vaporous spray?