Here's a classic Catch-22, if ever there was one. Given the excellent possibility of failure over time, you'd think that manufacturers like GM would incorporate some sort of alternative method into the Blazer (aka S10 or S15) to open the hood of the cable fails. But the hood mechanism isn't supposed to be easy to open without pulling the cable, forcing you to take some extreme measures to defeat The General's engine security methods.
Latch Basics
Most hood latches work in the same basic way. Inside the latch is an "r" shaped piece of steel, with the release cable connecting to the long, bottom leg of that "r". The short, upper arm of the "r" slots into one side of another "W" shaped rocker latch. The bottom of the "W" attaches to a pivot, and the second open space engages the "U" shaped bar on the underside of your hood. When you pull the cable, the short leg of the "r" pulls out of the "W", allowing the "W" to pivot and release the bar. A spring under the hood pushes the hood up so that the bar rises out of the "W".
Cut the Grille
Seems extreme, yes, but probably not as much as you're thinking. In order to get to the hood release mechanism and cable, you have to go through the grille. But the problem here is that the openings in this grille are too small to get any tools through. Normally, the headlights must be removed first to remove the grille, which requires opening the hood. You can cut the plastic grille or smash it with a hammer; doesn't matter, since you'll need a new one anyway. Fortunately, grille sets are pretty inexpensive can usually be had for less than $50 or so online.
Pull the Cable
You've got a couple of options once you get the grille out of the way. The first and simplest is to cut the plastic sheath around the cable and pull on the metal cable within with a set of channel-lock pliers. Use whatever you need to to cut the cable sheath off so you can get to the cable itself; a box-cutting utility knife will work. Hold the blade at an angle to the sheath and cut away at it till you get to the cable. Once you do, simply grab it with your pliers and pull.
Unbolt the Mechanism
The latch mechanism itself is secured to the radiator core support with a pair of forward-facing bolts. Once you get the top section of the grille out, you should be able to access the latch mechanism bolts from the bottom using an open-end wrench. You'll still need to cut the cable with a pair of wire cutters, which doesn't matter much if the internal cable broke off at the latch mechanism itself. However, once you remove the bolts and cut the cable, the hood should lift easily from the core support. From here, it's a matter of replacing both the cable and the grille, then bolting the latch back onto the truck.
