please please help emergency

01 galant gtz 3.0 v6..was running great and i mean great. went to change the front o2 sensor under the car. know it wont start full power and everything but no start. WTF did i do wrong . all i did was shut it off, pop the hood, find the sensor, unplug, unscrew, install and plug the new 1 in. i checked all the fuses (is there a relay.) 30a ign fuse is good also..