Please, has anyone else had this happen? Where should I look?

 

Without actually checking ,physically ,your installation work, You might consider disconnecting any wring you made to your vehicle. I suggest this because we have no idea where you tapped into for power or anything else.
If everything was fine before your addition, there is a good possibility you tapped into someplace where you shouldn't have..

Not knowing more info, you might also check all the fuses. Sometimes a wrong connection could cause a fuse to open.