my 2002 olds alero sometimes wont start it turns over but wont fire up

scan anti theft codes and post

Turn the key in the on position for 10 minutes till the security light stops flashing, when doing this make sure to turn radio off and pull the cars e brake so you don't drain anymore unnecessary power, turned the key back off and it should just fire right up, I've had it happen 3 times no, first tworld times costed me $400 CAD