Replacing the rechargeable battery has been covered elsewhere (including YouTube) but I thought it might be useful to detail my experience of getting the case open without losing any fingers.

Cutting open the keyfob case is a lot easier once you know the position of the internal ultrasonic welds.

Before you start, note the following:
Do not open the fob if the battery simply needs a few hours to recharge. Mine are probably 8 years old and well past their prime.
The weld on the key side is on the inbound side of the recess so there is no point in trying to access it.
There is also no need to cut along the thin end of the fob (nearest the padlocks) since this weld will give way as the case is wedged open from the wide end.
If you don't cut the other two welds, as below, you may well damage the case and the circuit board.

Use a sharp, sturdy craft knife or a thin Dremel wheel to make a narrow cut along the split line on the side opposite the key.
The weld could be as much as 2mm deep so a Dremel is the quickest and safest option but don't go any deeper than you have to.

Continue to cut around the corner into the shallow recess and under the key retaining latch, taking care to protect the latch.

Once you have cut through these two sides, slowly wedge the fob apart from the wide end and the internal weld should start to give way. Do not insert anything that might damage the circuit board or delicate switches.

Even though this was my first attempt, I was surprised to find that the case snaps back together very neatly and the emergency key holds the wide end closed.

With a degrease and a dab of silicone sealant along the welds, it would be hard to tell it had been repaired.

I hope you find this helpful.

Handy tip. I found a pair of circlip pliars inserted in to the blade slot worked a treat. Only took the one go and the fob popped open.

There is a very good illustrated article on replacing the battery in the October 2015 edition of the Land Rover Owners International magazine.

Bill Life Honorary Member of Wallasey Motor Club.
Licenced MSA Radio Operator for 35+ years.
Rallying is the only sport.