Presumably the fob opens the.doors from what you say, so I imagine that the air line to the trunk opener has broken. In that case so done will have to get in the tripung and remove the passenger side upper, lower and the rear trunk panel.
This will enable you to see the yellow air line from the pump to the trunk lock and replace it. If you are lucky you will find the break inside the rubber corrugated hose at the top of the hatch on the passenger side, of so a repair may be done using a larger hose that fits over the yellow one.
I would not spend any time looking for a lock under the license plate inthe hole there, seemingly some have been able to open the trunk using something to trip the lock.