My sisters G6 won't start. She had her battery tested at auto zone and they said it was fine. But, when she tries to start her car she gets nothing.
Check the starter it may be bad.
Starter, Alternator, or it may just be bad battery cables/ends.
Search Maintenance & Repair Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Maintenance & Repair Experts