Hello, new here. Bought a 2002 Deville off a buddy I used to work with. Story starts, it was setting, rat chewed up the air filter, kept over heating, and wouldn’t run after a few miles. Anyways, he took it to a local shop where I live and they had it for 8 months and did nothing to it. So he got it back, and it’s been setting since. I bought it off him, put new battery he had for it on it. Been working on it in my shop, and every single sensor was unplugged. I got everything I could find back together. He also had a new ECU for it. I know the new one won’t work without being programmed, so I plugged the old one back up. Got everything working on it, radio, dash, etc. except starter won’t kick over. When I turn key over, everything goes dark. Checked all fuses, reset security system, but haven’t gotten to starter yet since I was trying to do everything possible before pulling intake. Few minutes ago, I unplugged what was supposed to be fuse #29, for the ignition, but instead it had a relay. After that, the ignition is now locked steering wheel and everything. Any help would be greatly appreciated, don’t know much about these cars.