2016 Tacoma tailgate won't unlock

I just had a tonneau cover installed on my Tacoma and I locked my tailgate with my key about 3 days ago and I went to go unlock it with my key and it will not unlock and of course the tonneau cover is you can't access through it without having tailgate open and it is not a key fob it's a key anybody got any ideas

 

Does the key turn and doesn’t unlock or won’t the key turn

 

Push it [tailgate] inward hard while turning the key.

 

For what it's worth, I used to lock my tailgate manually with the key (Manual transmission has physical key) prior to installing the OEM automatic tailgate locker. I never ran into an issue unlocking or locking. I think fxntime has a good idea. You may want to ensure the gate is fully closed and try to engage the lock again. I can see how a tonneau could potentially cause the tailgate to not shut properly, which is hopefully what is happening here. Best of luck.