The outside latch on mine broke about9 months ago. The inside still opened with a bit of work.

Try removing the door mounted tool kit and the inside latch surround. You may be able to pop off the door panel. You can then slit the plastic behind the door panel. This should give you access to the latch assembly and linkage.

Mitsu # 6 - 98 6G72 Montero Sport, Locking Rear Diff, Aisin Manual Hubs, 31x10.5

Mitsu # 7 - 02 6G74 Montero Limited