No power to anything

I just pulled a 68 four door Torino out of a barn and trying to see what needs work I found that nothing works. No lights no horn key won’t engage starter no power to anything. I haven’t traced any wires around yet. I replaced fuses under dash but still nothing. I can engage starter by shorting the solenoid so there is power from the battery. Could bad grounds cause everything not to work at all? This is my first time posting and thanks in advance for any input. I hope to see this beautiful car on the road again soon.

I’m not having an issue with it running my problem is I can’t get any electrical accessories to function. Like I said, no headlights, radio function, turn signals, buzzers or horn. I’m looking to find out if there is one thing that can fail that would cause all electrical power to go out. And I’ve looked under the dash and the hood for rodent damage and other than a hole on the front seat. But if there is one circuit that could cause the issues if severed then I’ll not rule out a chewed wire. 

  Check grounds first. Then put a test light between a disconnected battery and the battery post. If the light has power without key on or a radio/clock running, there is a short somewhere. My bet is the one of the grounds or a  few are bad.

sounds like a main power wire...