I just put a new battery in my '70 LS-5. All of a sudden, nothing electrical works in the car, no dome light, no clock, no nothing. The battery has voltage, and the connections are tight. When trying the ignition, there is nothing. The last time I drove the car (last week), when leaving my destination the ignition failed, everything blaked out, but then mysteriously came back and I was able to crank the car and get it home. Can someone please diagnose this for me?