Before anyone starts slicing into a key card, they are a very delicate item and you could easily turn a repairable item into junk, or badly cut your fingers ! So unless you have nothing to lose or are very rehearsed in this type of repair it's probably better to send your card away to a repair company !
Having just had the pleasure of opening a 3 button key card I thought I would post up a few pictures that hopefully will be a good reference and help anyone else faced with the task of opening one of these cards.
There's quite a bit of information floating around detailing how to open & repair a 2 button key card, there's even videos on You Tube showing the procedure.
The 3 button key card is slightly different in design and this makes it difficult to cut certain areas.
(Some repair companies won't touch this type of card because of the difficulty in cutting them open)
The pictures below are to show the difference between the 3 & 2 button cards and where the 3 button version needs to be cut to open it.
Cut right round the card, make sure to only let the blade go in as far as you need to so you don't hit the circuit board.
Leave the areas marked in Yellow & Red in the pictures below until last.
To get to the Yellow area the side of the card needs to be held open, wedge it open with some folded card or something then insert the blade in over the top of the rectangular component, be very careful when making the Yellow cut.
The last cut to make is the Red area, once again wedge the card open with something and slowly cut the Red area, be very careful as the card case is very thin in this area.
You should now have the card open, if you have took your time and been very careful there should be no damage to the card or yourself.
The 3 button key card compared to a 2 button version :
The 3 button key card cut open :
The difficult to cut areas :