You can't loosen the screws until you get the door open. You're going to have to push/force it right to left, to unlock it. For it to be that tight, it must be jammed there is a pin that rides in a slot to to lock it.
Here is a photo of the pin, that is mounted/inserted in the top of the freezer door. The other photo is the sliding portion of the lock attached to the bottom of the door. The pin has to slide in the bottom portion of the "L" shaped trough (lower portion of the "L"), then the doors pull open.