Land Rover Repair: Remote on Key / Battery, correct polarity, battery press

Question
I have a 2002 Discovery.  The keyless entry has stopped working and I thought it might just be the battery.  I took the key into a Radio Shack and they were fearful of messing up the key trying to open it to replace the battery.  Is there a trick to opening the key?  Are there diagrams to show how?  My owner's manual does not show anything.

Answer
Insert the blade of a small, flat bladed screwdriver into the slot at the rear of the handset and prise the back from the handset.

Slide the battery out of the clip taking care not to touch the circuit board or the battery contacts.

Press and hold one of the buttons for at least 5 seconds.

Fit the replacement battery ensuring that correct polarity is maintained (+) side facing upwards. Avoid touching the flat surfaces of the battery.

Press the 2 halves of the handset together.

Check that handset operates correctly.