94 mustang Gt

(1994 mustang Gt w/20k miles) Need a little bit of help here. So recently I swapped my radiator due to rust build up. When trying to start the car my cooling fan is constantly running and my car doesn’t turn over. It’s as if the car thinks it’s overheating. I’m getting spark and fuel. I replaced the ECT sensor and got nothing. I replaced the bcm which has a fan relay inside it, also got nothing. Checked all my grounds. Still got nothing? Does anyone have any insite on why the fan keeps running when the fuel pump is priming?