This is about as easy a piece of maintenance as there is, so what could be wrong?
Battery was not sufficiently charged prior to install. Check with multimeter.
Loose or missed connection. Recheck your work.
Blown fusible link. This is some sort of fuse that cuts your battery out in the event of a significant accident. Don't know how this could be blown, unless...
You hooked it up backwards... Always possible, and if so, you may have burned up all sorts of electronic gizmos.
Another potential problem is if you disconnected the positive terminals first, and they flopped around and touched anything that was grounded out to the chassis, you may have fried a fuse or a component.
Failure to register the battery will not cause this problem, it only affects the longevity of the battery secondary to improper charging.
If it is not the first two, it sounds like something probably fried, and maybe a bit of expertise is required.