Lots of people are at work bro, bumps less than an hour apart are unneccessary.
I have no idea why your car would do that after changing a headunit. My guess is that it's unrelated since you put the old unit back in and it still didn't work. Since you were working on the electrical system, you may have overloaded a circuit and blown a fuse or flipped a relay or something. My first thought would be to check all the wires behind the head unit and make sure there's nothing naked (no sheathing) that could short something out, make sure all connections are tight and wired properly (sounds like they are since the h/u works) and then move on to the fuses. My car wouldn't start once cause I jarred the ignition fuse loose somehow.