Why does my GFCI show a green light if it isn't giving any power?

Nine times out of ten, when those buttons are unresponsive but the light is on, the GFCI has reached its end of life or was wired incorrectly from the start. Since you mentioned the buttons don't click or move, the internal mechanical linkage has likely failed. Modern GFCIs are designed to fail in the 'open' position so they don't leave you with unprotected power, but older units can sometimes keep that status light on even when the internal bridge is broken.

You need to pull that outlet out of the box to check the wiring. There is a strong possibility that the previous owner swapped the **Line** and **Load** wires. On many newer GFCIs, if you feed the power into the Load side, the green light will actualy turn on, but the outlet will refuse to reset and won't pass any power to the face of the plug or the downstream exterior outlets. It's a safety feature to prevent improper installation from leaving a circuit unprotected.

Grab a cheap multimeter or a non-contact voltage tester before you start swapping parts. With the wires disconnected and the breaker on, identify wich pair of wires is actually bringing the power in—that's your Line. The other pair going out to the yard is your Load. If they were swapped, fix the orientation and see if it resets. If the wiring was allready correct and it still won't reset, the internal circuitry is fried and you just need a new $20 replacement.

One more thing to look for is a loose neutral wire on the Load side. If the connection to those exterior plugs is loose at the garage outlet, they won't get juice even if the GFCI itself is healthy. But given that the buttons feel dead to the touch, I'd bet money on a mechanical failure inside the device. Replace the outlet, make sure your Line and Load are on the right terminals, and those exterior plugs shold fire right back up.

Wow, I'm brand new here and just learning about all this! I had no idea the status light coud lie to you like that. Since you're alredy looking at the outlets in your garage, have you ever seen those ceiling-mounted retractable cord reels? I’ve been dying to install one so I don't have extension cords all over the floor, but I wonder if they're a pain to wire into an existing circuit or if they need their own dedicated breaker?

I had this exact thing happen in my shop last spring. Green light was staring me in the face but the table saw wouldn't budge. I spent an hour messing with the wiring before I realized the outlet itself was just toasted from years of sawdust and humidity. If those buttons don't have a solid 'click' when you mash them, don't even waste your time troubleshooting the downstream stuff. I just swapped it for a new Legrand unit and everthing down the line started working immediatly. Sometimes these things just give up the ghost internally even if the LED says otherwise.

Quick update — I replaced the outlet today and everythign is back online. You guys were spot on about the mechanical failure; the old unit was totally toasted inside and had no 'click' left in it. I guess that green light realy can be a liar! Thanks for the help, saved me alot of troubleshooting time.