trunk Kia Sodona Minivan can't be locked

I have a Kia Minivan Sedona and just find out the the trunk can't be locked. Also the side door can only be opened from ourside, this has been a long term issue. I didn't bother to call Kia for a long time. When I called last month, the 5 years warranty just passed :-(

So is it an small mechincal issue or electronic issue? Any easy fix?

Thank you so so much!