You need to use the car's built in Trouble Code system to perform your own diagnostics. Read and study the sticky thread at the top of this group of threads - "How to pull codes". Get any stored codes, then return to the sticky and use the URL with "obd2" in the link to get to a Master Index of links to P,B,C, and U codes.
Come back here and post the codes, definitions, and whether each is Current or History.
How old is the battery, and when was the last time you cleaned all the battery cable terminals and connections.