For added context, the hydraulics on the gate were recently replaced. Before I replaced those it was very difficult to open the gate (very heavy), and it wouldn't stay open on it's own. After the hydraulics were replaced, everything worked fine for a few weeks, then all the sudden the gate wouldn't automatically open. It's almost like the gate thinks it's still locked, so it doesn't even try to open.
It could be a couple of things.
Your first post stated that you can hear the motor running but no action so that eliminates the possibility that your liftgate switch is turned off and it indicates that you are getting power to your motor, or so one would assume if you're hearing it.
The linkage could have come loose which you can try and check by grabbing the lift rod and seeing how much play you have.
I believe there is a clutch on the motor and those sometimes fail.
There are also a gear train that can strip out and if your gas springs failed, it could have overloaded the gear drive and stripped a gear.
Here is a video that discusses how to get to the motor. There is a couple things the guy covers at first but around 2:45 he gets into the lift motor.