my 2008 will not start after sitting for 2 days

take it back to the dealer and tell them they did not fix the issue you brought it in for.

thank you Kbro, guess what i did take my car in for service(GM) and they ran it down as a starter problem($337) the first time i let the car sit for 2 days last week i took it back on 4/23 and picked it up on 5/1 and had to get a jump from the service dept.No charge! no ansewer for problem! except may my battery doesn't have enough cranking power.(700 cold cranking just bought battery at Kelly's Auto Dec 26.12 so i will take my truck to a private shop and hope they can find the problem. so thanks again Kbro

ignition switch under column.