abarli65 Welcome to the forum

Will the hatch stay open if you open it manually? the struts may be weak and or the opening mechanism gears may be worn or broken...
If you hear it operating, I suspect the latter, however the struts should be inspected...

The last time I had it in the shop, I told them if they would gaurantee that they would fix it with the part they wanted to put in to go ahead (about $500) but they were not goig to nickle and dime me. Well the part didnt fix it. They had a used suburban that they took parts off of and said they found the problem and it would cost $850 in part adn 4 hours labor. My wife wanted it done so I bit the bullet. Well, that part didnt fix it either. When I got the suburban back, they replaced 2 modules and a lock for a total of $1065.82 , but no labor.

Im satisfied that the door is fixed but frustrated that even the dealer cant figure out the root problem.

I have replaced the struts. The lift mechanism does not fully run, but just whines for a sec.

I have all the plastic pulled away and can see all gears and motor.

That's a whip Steve. I want to sell this thing with a working tailgate, but don't want to have to drop a grand on it to do so. What to do, what to do.

You've done good if you have it to the point of being able to see its workings...
Will it work if you assist it? I don't have that option but can only offer my troubleshooting opinions...
if its making sound then the motor is getting power
It could be the driver/module for the motor, not providing the current needed..
It could be the motor...
might try disconnecting and reconnecting the electrical connections to ensure its all a good connection...

If the motor is turning but the gears are not and they're plastic, possibly a stripped gear.

The gears to lift the liftgate are definitely not stripped... they some sort of metal.

I now pretty much use the button on the liftgate itself. Once I squeeze it, the latch unlocks and I have to pull on it just a little to get the latch off the loop thing... I hold it for just a second before the liftgate mechanism on the left releases it. When this first started, I had to 'pop' it sort of to release it, but now it does it pretty much on its own, or just much easier.
A few seconds after, the latch starts to whril, click, and sputter.

My neighbor is a service advisor for GMC... we looked this up on the GM service website and there are so many tests and voltage checks on the lock, modules, and motor... I have an ODB2 reader and I have no codes. I may just bite the bullet and take it in and hope for the best.

My 07 Suburban LTZ had the same problem a couple of days ago, however I attributed that to the -30 degree weather we were having here in ND. It works again now. Does it work off and on? or is it hard broke?

Fixed
 

After everything I have read here and taking all the panels off, watching and listening to my system not work, I decided to have my neighbor take it into his dealership.

Turned out to be the latch mechanism.

They replaced it and had to re-flash it. These things have software involved, so not something that can be fixed at home.

$400 fix. Oh well, it is what it is.

2008 chevy suburban
 

I have the same problem and before i found this forum i have had also replaced the motor already :( . I have also found on another forum Power Lift gate problem.....Help - Chevy Tahoe Forum | GMC Yukon Forum | Tahoe Z71 | Cadillac Escalade - Tahoe Yukon Forum that it could be the latch inside the door.

I gone order a latch and try to replace it.
greetz
Hans