I can't start my car. I bought a key fob on ebay, programmed it using the instructions in the forum. It locks and unlocks as it should.
I knocked out the roll pin and pulled the blade from the old fob and had to tap the blade into the 'new' one as it was a tighter fit. I used a rubber mallet and just a small amount of force and reinserted the roll pin.
This morning I blipped the car to unlock it and turned the key, the ignition light came on but the starter won't engage. Can I have damaged the immobliser chip by tapping it?

 

I believe the problem is that there are three parts to your key:
The actual cut metal key (good)
The key fob (battery powered and opens doors wirelessly)
Then there is the key transponder which is in the small plastic part of the flip part of the key. This transponder MUST be programmed by the dealer. We have no way around this unless you have 2 original keys!

 

My x-type came with just one key - as always with me :-( so very first thing I did was get the key cloned at a keymakers.. that way I can get in no matter what and start the car, and if worst comes to worst can always use it to program a new remote control.. ideally would have two proper keys - but last time I had to get two keys it cost me over £200 in locksmith charges to get the car reprogrammed - so for me this was the best option... hope that is of some help..

 

You should not have swapped the metal tibby key part. You seperate the remote button from the other half and install your old key half to the remote part. You removed the transponder from the equation that why your car wont start

 

In other words, if you have trashed your old fob ... better dig it out of the garbage quick!

 

sounds like you've only programmed the button part for opening the doors, you also need to program the key part to start the car.
You can do this if you already have 2 keys that will start the car, if not it's a jaguar dealer or an auto locksmith.

 

Thanks, you prompted me to think clearly about how the key works.
This morning I changed the blades back to the original positions and swapped the button bits over.
Bingo, working key!
Thanks to all the contributors, saved me a fortune, I even glued a small piece of plastic onto the switch for the open button on the worn fob so my wife can at least get into the car when we are out together, she shops a lot and I can go for a drink while I wait. I even got brownie points for that, a result I think.
Thanks again.