my 2005 Pontiac grand prix Car won't start. No clicking no lights, no nothing Was running then just quit wont start

Try to jump it? If nothing at all, check mega fuse, check battery cable to starter, alternator and relay, check ground connections, check fusible links. (mega fuse may be mounted on inner fender and not in fuse box).

Did you clean any corrosion on the loose battery cables when you tightened them?

Yes he did. But he is now in the hospital but I will have me son recheck that. Thank you

Hope the cleaning solved your problem.

Has anyone figured the problem out I am having the same thing, no lights on dash starter won’t work I just hear clicking