No power to radio, horn, or remote unlock

I'm not sure if there is a previous thread associated with this, but if there is, please let me know. I'll delete this post immediately.

I got an aftermarket HU and decided to do the work myself to replace the OEM one. I know for a fact that I have all the wiring hooked up properly ( I had a friend of mine double check for me) and all of the fuses are fine ( I checked myself), but there is no power at all going to the new HU or the horn and my remote entry doesn't work anymore either.

I know that I didn't disconnect the battery when I initially hooked it up, but I didn't think that would cause such a problem. I could just be horribly wrong, though. Everything else works just fine.

Let me know where you think the problem may be stemming from. If it was just that I'm dumb and now need to replace something expensive, I'm at peace with that. Someone please let me know.

BLKTSTC

There is usually more than one fuse related to the radio. Generally the ignition fuse is in the passenger cabin fuse box and the constant is in the engine bay fuse box. Don't remember off the top of my head about the p5. Grab a multimeter and check at the radio harness which wire doesn't have power.

check ALL you fuses again, one by one.

Make sure the grounding points are still ok

Yep - one fuse for door remote/int lights and... so yeah, check interior fuses...