A well known E31 problem.
First you have to pull the door handle all the way up to open the door.
It ends with shortly after with a non functioning door opening mechanism.
The reason is a broken part inside the door handle.
BMW can't deliver neither a spare part nor a complete door handle.
This repair kit fixes the issue.
It covers both door handles and comes incl. a necessary 2mm drill bit.
The 2nd picture shows a broken OEM part.
Installation instructions (link)
go to post