Dell Latitude D531 wont start

Ok ive done a lot of reading on this and nothing has worked so far. With both memory cards in it the power lights come on and caps lock blinks but thats it. With the bottom card removed it will turn on and go to bios. I ran the onboard diagnostics and it didnt have any errors i know its not the memory card because it still works if i switch the cards. When bios comes on i can go to f1 to continue and f2 to run setup utility and f5 for onboard diagnostics. When i press f1 it says missing operating system f2 brings me to settings and f5 does diagnostics which all passed. Any help is greatly appreciated. Could it be the little battery by the bottom memory card?