probably you need to check the connections in the pushbutton on the tailgate - there is a 4-pin connector... take the handle off (4 torx screws), clean the connector... if still not good, maybe it is time to buy a new handle...

This is for E53, right?

__________________
E53 X5 4.6iS
147K mi - Sold May 2013
Tireprints left in:
USA, Nicaragua, Costa Rica, Panama, Russia

E53 X5 4.8iS built 2005-10-17
66200 mi - June 2012
96000 mi - June 2013
112000 mi - June 2014
OEM fire extinguisher
OE first aid kit
OE tow hitch
OE TV module
OE aspheric mirror
K&N air filter
black/white badges
rear camera
4-channel video recorder

Here is the list of things I have done to the X