I just did the heater core and now the car won't start. No lights come on the dash, cant even put on the hazard lights. It won't even attempt to turn over. All I hear are constant relay clicks under the dash.

The battery only shows 6 volts. Whats interesting is it shows 12v if I disconnect the positive terminal from it. I can't get a single thing to turn on or work. None of the lights will turn on, when you press the hazard button or horn, all you hear are fast clicks from what sounds like a relay under the dash. There is a light under the dash that's on, next to where your legs would be if sitting in it. Thoughts?

Here's a video.

 

OK, so I just had a learning moment. Apparently the battery can show 12v, but if it's low on cranking amps then it won't give power to anything in the car. Check out the stats on the battery I just had checked! It was suppose to have 700 CCA. Bought a new battery and everything is now fine. Sorry to bother....