OK, first problem, you must have blown a fuse when you got the short, and the "mechanic" bridged over the fuse to let you start. Better solution is replace the fuse and get rid of the extra wire. problem 1A, Sounds like your batteries are not charging. replacing the fuse may solve this problem. problem 2, you were wiring into a hot circuit, now you know not to do that. find the fuse for that circuit, pull it, then do your wiring. problem 3. "mirror touched the body" sounds like your short was internal to the mirror. fix this before you go back to problem 2.
Take these one step at a time, work on problem 1 first. Do you have a voltmeter? A diagram of where the fuse boxes are?
Jim and Valerie, 2005 Winnie Adventurer 37B, 2014 Subaru Forester Toad, hitches, brakes, anti-sways, autopilot, gourmet food on a Social Security budget.
"Wave as you go by."