The seat has to be locked back in place and in the up right position and slack in the belt for it to release. You can knock the catch over so you don’t need it lock all the way back if it helps to get some slack in the belt when it’s in the upright position but if not you will need to undue the bolt holding the bottom so you get some slack it should then release. To do this remove the two bolts under the seat one on each side and the base should then lift up and give you access to the bolt that hold the bottom of the belt. Then with the it locked back, upright and slack in the belt it should release.
UK Chrysler Jeep Master Tec.