I had mine get stuck a couple of years ago- one side released but the other didn't. I had to remove the plastic inside shell and operate the mechanisms by hand to get them both open.
Those electrical latches are fairly simple. I think next time you have the rear hatch open you remove the plastic shroud and check them out- simple oiling may help. They also might be slightly out of alignment- there are several bolts holding them in and you should be able to adjust them some. There is a wire coming out of each- that is the fail safe open cord which will operate them with no power.
I just kept my plastic shroud off after that- I made an aluminum plate to cover the interior of the gate and left the latch hardware exposed so I could get at it easier.

When mine has this problem, the issue is the struts not having enough power to pop open the release.  Does you lid stay up or has it bonked you on the head recently?

Chris

This was a problem since they were new on the showroom floor. Every one of them has this issue and the answer is to pop it twice. You have to be lifting on it, though, so if you don't have the keyless entry remote, you need to use the key in the lock on the tailgate. The hatch is too heavy and the angle of the gas shocks is too great for it to open correctly.

I had this problem with mine until I soaked the release mechanisms a couple times with WD-40. I did this about 2 weeks apart.