Take the door panel off the inside of the door. (Should involve screws at the bottom, plus bolts through the interior handle. Then pull out at the bottom, and lift upward Google for expedition door panel removal for more specifics if needed).
It sounds like the exterior handle linkage is binding against the lock button linkage. Actually looking in while pulling the handle would confirm. You then should be able to just bend the rods a bit to move them apart.
Here’s the Suburban with kayak inside and the lift gate panel on the floor. If you have a Suburban / Tahoe / Yukon in the same situation where your lift gate won’t open, the only way to get it open is to pry the lift gate panel just enough to access the locking mechanism. Take a long flat head screwdriver, slip it into the top section of the panel and start pulling away. The panel is made of a flexible plastic that will bend a fair amount, so don’t be afraid to put a bit of elbow into it. Once you see the locking mechanism, you’ll want to grip the back side that moves and twist counter-clockwise until the door pops open. Once you’ve done this, call GM customer service and tell them that their engineers should be fired for not having a manual release. If there is an accident / fire up front, wouldn’t you like it if your kids could escape out the back? Yeah, me too.
If you’re lucky enough that you can open your door (or maybe it doesn’t lock to begin with), then it’s a little easier to pull off the panel. First, take a socket wrench (9mm, I think) and remove the bolt under the leather handle on the inside of the door (the one you pull down on when your lift gate is up). After that, insert a flat head into the space between the panel and the door and pry open. There will be around 4 or 5 contact points to disconnect. 
The two last things that stand in your way are plastic hinges that hold the panel to the door frame. With the lift gate open, push the panel toward the car, then spin it an entire half-circle around the hinge in the picture. After that, the panel should pull right out. Now the locking mechanism should be nicely exposed. 
Here we see the lift gate handle at the bottom, which is connected by a tension wire to the locking mechanism. Pulling on the handle causes the wire at the top to retract toward the right, turning the locking mechanism counter-clockwise. 
However, pulling the handle does nothing when the mechanism is in the locked position, because it doesn’t engage the other tension wire / tailgate release - it just simply moves by itself. When the mechanism is unlocked, pulling on the handle will engage the release mechanism and pop open the door… when the locking mechanism is working, that is.
Here is a properly unlocked door: notice that the black plastic piece (on top of the copper) is slid all the way to the right. You can see that if you rotate the lower copper piece, that it will force the black plastic piece to turn, thus engaging the door release. 
Here is why your Suburban tailgate won’t unlock. I’ve just pressed the unlock button on my key FOB and you can see that the black plastic piece has NOT slid over to the right. This means that the door is still LOCKED as far as the mechanism is concerned. No amount of yanking on the handle will open the lift gate at this point. 
Zooming in for a close-up, you can really see where the problem is. Gear heads will realize this is a major problem for all sorts of reasons. First, if your door lock actuator is banging against this metal part every time you unlock your door, it will wear out the part extremely fast and you’ve got yourself a busted door. Second, even if you replace your actuator, you’ll just bust it again if it keeps ramming this part. Most importantly, the question is how this is happening to begin with? My Suburban was working fine until I put in a factory replacement handle. 
I’ve read a whole ton of reports about Suburban lift gates, along with Tahoes, Yukons and other GM cars failing and drivers stuck with unlockable doors. I believe this type of careless “few millimeters off isn’t important” BS is likely to blame. That’s why some people may have locks that work only half the time, or some work after their actuators are replaced, but fail soon afterward. My two-cent opinion - back to fixing cars.
So what we need to do, is make some space for that locking (technically, “unlock”) mechanism to engage fully. On my Suburban, this meant giving the metal tensioner just a little more slack - 2mm would be all I need. 
First, I pushed the handle wire mechanism over to the right and then pulled out the metal ball and wire. After that, I pinched the blue wire cap and pushed it out of the metal holder.
You can now see that there is a lot of visible space between the locking mechanism and the metal. Pressing lock and unlock on my key FOB easily moved the unit back and forth successfully, so I knew it wasn’t a problem with the actuator. Now comes the disclaimer part.
DISCLAIMER: Attempt this section at your own risk, you are responsible for your own actions!!! Not seeing a lot of options, I decided I would take a somewhat drastic approach and bend the wire holder closer to the locking mechanism with a pair of pliers. I only needed about 2mm, so I felt this was acceptable without busting the car too much. Needless to say, this is not a graceful fix nor one I really wanted to do, but there appeared to be little other options other than cutting your own tensioner line (adjusting the line would be the most logical method, but I pinching and pulling got me no results) or finding some concrete way of bracing the line closer to the locking mechanism. If you come up with an elegant solution, please let me know. 
Phew, finally - the fixed tailgate lock! You can see there is just enough room for the mechanism to engage and that the handle tension wire is snugly seated into its new home. I tested the lock about 100 times to be sure that everything was working as it should and I advise you do the same once you get to this point.1,509 views
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how about when you lock or unlock manually inside the car or, when you lock or unlock the door with the key.
here's what the latch looks like inside. so you are saying the inside lock button pulls down when you lift the handle? BY the illustration, it should pull up. Do they both work ok when unlocked?
#1 is the outside door handle rod.
#3 is the lock rod.
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