So I was upgrading my horn and I had to move the hood release cable out of the way, and I thought I put it back in place, but when I tried to open the hood this morning the interior hood release lever pulled all the way back without tension. I tried tugging on the cable and fiddling with the latch release under the hood, but I can't open the hood. Any tips? Thanks.

 

same thing happened too me what did you end up doing?

 

If you can access the cable from under the front of the car you should be able to manually open it that way. That may work. If not, u could always try to open it the same way through the front bumper somehow.

 

Same here. Upgraded the horn, now I can't open the hood.

OK, got it fixed. The hood release cable runs right by the horn. It is very easy to accidentally dislodge it from the hood release mechanism. The blue plastic end can pop right out. There isn't much to hold it in.
To fix:
Set the parking brake.
Safely jack up the front of the car.
Remove the round plastic clips from under the bumper and two of the gray plastic Phillips screws.
You don't need to take them all out, just enough so you can pull the lip of the bumper down and get your arm in there.
Reach up and pull the hood release cable firmly and the hood pops open.
If the metal cable came completely off, you may have to pull on the springs and levers on the back side of the latch to get it to pop the hood.

Remove the same covers you did to change the horn.
I removed the hood latch assembly so I could get at it better.
Put the cable back in where it is supposed to be. Have someone pull the release in the car to make sure it works.
I used a piece of wire and tied the blue plastic piece to the latch so it won't happen again.
The hood latch is adjustable, so line it up the way it was before as you tighten the 3 bolts.
Test it a few times to make sure it is good. The hood should just be tight enough so it doesn't rattle. Too tight and you'll have to yank the release really hard.
Put all the covers and clips back.