Ok i have a 88 supra went to start it everything went dead lights dash radio what could it be?

like me and my friend wire brushed some of the wires to the battrey got alil more flow but idk if its the fuses wires or what maybe someone might no not even enough power to rule windows up and like when i push the brake what lights where on like the door light and the side lights on the door would shut off and come back on when i push the brake