I can confirm this worked; change units to km/litres using the mode and +/- keys on dash, then run service reset with ELM 327, when complete check "service" indicator using Mode +/- buttons, and it should now show 20000. If so then you can change back to miles / gallons using the Mode butt...

Where exactly did you change units? On licensed version of FES the distance to service shows 20000 km. Reset procedure connects and shows it's complete after a short time, but the service due in distance shows 0 km. Mode key on dash also shows 0 distance to service.

Regards
Steve