Theres a cable that runs to the inside handle, its not uncommon for them to break. If you can open the door from the outside its most likely the cable. To remove the door panel, first remove the tweeter speaker cover at the top front of the door, by the side mirror, there is one screw behind it that needs to be removed. There are 2 screws under the armrest, then 1 in the the interior handle surround, after removing the screw you can pull the handle surround off. Once all the screws are out, the panel is just held on by pop clips. Either a panel remover tool or a flat head screwdriver will work, just take your time as most land rover plastic is brittle after a few years. Good luck.