A costly spark from not disconnecting the battery

I was putting in a new alternator on my landscaping van. I didn't pull the battery cables off first. My wrench hit the positive post and there was a big spark. Now the van's dash lights are all on and the radio won't shut down. I feel pretty dumb since I've done this job before (you'd think I'd learn, right?). Any tips for fixing the electrical gremlins I probably caused? Or stories about your own rushed repairs?