Only way is to take it to a stealer or someone with Autologic or Rovacom.
To clear the fault from the display will take all of 10mins. max. The stealer will rip you off-the Independants wont. If it's a "Hard" fault, and won't reset it will show up immediately and they should be able to tell you the cause. Usually, this display comes up if the instrument pack is removed without disconnecting the battery.