Your still messing the ground up probably, I grounded somthing to my car under a bolt and it looked fine, but then it didn't work and my friend looked at it and there was a whole extra layer of silver paint there that I thought was metal. You have to scrape the metal so the connection is 100% perfect, once youve done that, bolt it down, power it up and all else fails, check the connection on the battery, if there is corrosion (dirt) all over the metal and you just screw it on, it's NOT going to work. hope this helps.