2001 grand am

Need help with a 2001 Grand am..my sister drove up from west palm to avoid the storm she said the check engine light was on for a week prior to comeing up here and the day before she came up the oil light came on....she gets here and now the car wont start. I check the fuses they are all ok, I check fire its throwing spark and I hear the fuel pump coming on....I checkthe oil it was very low,enough to show in the dip stick I put oil in to see if it was the oil press. sensor tripping but nothing,..I plugged my neighbors comp to it and a bunch of bad codes came out one of them being the oil press.sensor....I replaced the oil press. sensor but it stilll will not start...I unplugged the batt. to see if it will reset the comp. but it still shows check eng. and change oil , and not starting......my neighboor is not home yet to use his comp.any suggestions aside from burning this car??? HELP PLEASE