My trunk pops open randomly on a 2011 regal buick.

The manual says there is a touch pad under the emblem.

https://www.manualslib.com/manual/538183/Buick-Regal.html?page=12

There is an Emergency release inside the trunk if you can reach in from the back seat. This page refers

https://www.manualslib.com/manual/538183/Buick-Regal.html?page=46#manual

https://www.manualslib.com/manual/538183/Buick-Regal.html?page=12

..

Visit the on-line store, know as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.
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It is most likely the latch assembly that is the problem, they are very prone to this, the whole thing is sold as one unit from the GM dealer.

If that model has a fold down section of the rear seat back, the manufacturer normally installs an accessible manual boot release tab in the vicinity of the fold down seat section just inside the trunk compartment.

If there is no fold down seat in that model or no manual boot release inside the trunk area, the rear seat needs to be removed so that you can access the trunk from inside the car.

take the FOB out of your pocket and drive for a while. if it still opens, check the latch mechanism to be sure is it fully engaging. The trunk may be popping because the latch is not fully engaged.

Do you have a button on the dash, or do you have a lever on the floor ?

Could be in the shifter switch linkage. Regals have a wiring harness that sometimes give strange problems, check the area near the right trunk support piston (open the trunk) . Harness runs along top right edge of trunk. Pull back the wiring harness plastic shield and check for broken wires. I have seen that area cause problems with the dash and turn signals also.

Yikes! You may need to remove the rear seat of the vehicle and trip the trunk latch from the inside.

I suspect you broke a torsion spring in the trunk. This can be replaced by you, but you won't be happy if it snaps you.

There is a switch in the latch assembly, the terminals could be corroded or the entire latch may need replacing.