My gate starts to open but then stops - Apollo 7000etl Slide Gate Opener Plus 2 371lm Remotes

Disconnect the power to it for 5 minutes to Reset it. Then press the Reset button. If that doesn't work call for professional service
https://www.affordableopeners.com/manuals/gate_operators/elite/miracle1/manual.pdf

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With the age of this vehicle, there is a good chance that the hydraulic struts can no longer easily lift, and keep the tailgate open...even though the electronics work OK.

reprogram the opening sequence in the control box
it should that the first gate opens then the second gate opens a few seconds behind it
closing is the reverse
you can program that only one gate opens
you can also program that one gate is a entrance gate where it opens until you stop it , then when you have passed through , press it again and it closes
read the operating instructions and follow the programming procedures closely

Clean all your cables to your starter and battery, sound like a starter solenoid issue, you may end up replacing. The thumb in the rear sounds like a bushing in the tail gate, I would inspect

Check to make sure there's nothing wedged on the bottom of the gate on inside of bed

first guess a bad electric motor
second guess to much resistance between the gate and the tracks try manually moving the gate does it get stuck at some point
3rd tighten any and all loose bolts throughout the system

n all probability the brake sensor on the pedal is starting to work erratically. This sensor sends a signal to the shifter gate, and the gate will not open unless the brake pedal is depressed. I had it happen to me, and the only solution until i replaced the sensor was to hit the brake over and over until the stop light worked. If the stop lights work, the shifter gate should allow the shifter to move out of park. This sensor/ switch is located about 3 inches above the brake pedal, and it is easily recognizable by the cable attached to it.

it was a loose connection on the circuit board in the romote keypad