If you have an early X5, there is a round 21 pin diagnostic plug under the hood, it would be in the compartment against the firewall on the passengers side. THAT is the one you reset the service indicator through if you have it. Once you twist off the cap, you will see this:
To avoid the special tool to reset it, stick a piece of wire into pin 7 in the diagram, turn the key on then ground that wire (you can use the strut mount nuts) for about 12-15 seconds, and when you pull it off, do a quick tap on the ground point again. That should do it!