2006 CTS no electrical power at all after alternator change
 

Had a starting issue with my daughter's car, so first changed the battery, which was old anyway, then just yesterday changed the alternator. Now when everything is back together, there is no power at all when you turn the key and the key will not come out of the ignition. I checked the battery connections and they are fine, and I'm slow charging it now but I'm sure it's not the battery because there was no power at all. Part of changing the alternator required me to remove the 2 ECU wires. Is it possible they are not on correctly, even though they locked in place? I'm planning to check the fuses after work today but I doubt I blew a fuse changing the alternator. Any thoughts on what else to check?