96 328i Loses all elec when u turn to ign 3

[StrictNine]

My 96 328i will not start. When I turn the key to the start position it makes one click, probably the starter solenoid, and then I lose all power to everything. I can take off the ground cable from the battery and put it back on in a few minutes and then I have power again but it still won't start.

Previous to this I had replaced my water pump because of a leak. I took it for a drive and when I came back and opened the hood there was coolant all over, I think I overfilled it as it was still a little overfull after it cooled down. I rinsed off coolant from the front of the engine and rad with a jug of water and then hit the starter to get it back up to operating temp and check for leaks, and that's when it wouldn't start.