Hello im in Canada. I had the exact same problem on my 2012 Cruze. So i tried every little trick everyone suggested.....but.....if you dont actually fix the problem you dont solve it.
So i opened the trunk and disconnected the harness wire that controls the liscence plate lights and the button to open the trunk....which is wired in sequence with the plate lights. And i left it for 2 days....guess what the trunk never opened. So that told me the trunk actuator (button) was fuct.
$85 canadian gets you a new trunk switch and liscence plate lights as one unit. you need to remove the chrome strip above liscence plate to replace. Easy simple and problem solved.
The original trunk switch was not sealed with epoxy so water enters and the switch (you will see when you remove the old one) will be rusted and corroded causing intermitant connection causing the trunk to release. The new switch you will notice has been sealed with epoxy resin. GM knew this was a problem and did nothing to solve it....left it as a easy repair for there techs to charge you a hour labour.
