focus shut down

I was driving my 2000 focus last night and all of a sudden it lost all power for a half second. The engine almost died and all of the lights went out but came back on fast. I tried to start it today but it wouldnt start. All that happened was the the key turning and nothing else. Also the ingion light is on. What could cause this ?

Also, when I try to start it the gauges go up and then back down and the lights blink. Sometimes it starts without a problem.

Have the battery and alternator tested. Check wiring going to the starter from the battery. Check that battery terminals are clean and tight. If these things are okay have the starter tested.

I had the battery and alternator tested today and they are fine. Just before this happend my ignition switch locked up. I used some wd 40 and tapped on the key to get it to unlock and work again. Then I put some graphite lube in the switch. I did the trip test today and it says "dtc 9318" which means battery voltage low. Now I'm clueless unlees I have a short somewhere. thanks