Usually, it's the hinge side of the two upper latches that won't unlatch, or both, and they're controlled by two rods on that center handle, with an interlock on the glass. Open it as a door with the glass raised, and pull the inner panel off. This will give you access to both latches, both rods and the inner handle itself. Sometimes, a rod's bent, sometimes, a rod clip is broken, but you should be able to see everything. Just remember, the handle is interlocked to the glass assembly; it has to go all the way down before the interlock is moved in order for the upper latches to release. Hopefully, that helps.
