keyless on 2003 Infiniti M45

I have keyless entry on my vehicle. While changing the battery a little piece of what I think is carbon fell out and I lost it. Now the key will not work. I went to the dealer and they do not carry that piece. They want 6 hundred dollars for a new key. Thank you

Asked by for the 2003 Infiniti M45
There is no other option, find the chip, which is what fell out, or get the new key. The chip is specific to your car, an can not be matched. Meaning that not only will you need a new key, but your car will need to be programmed for the new key as well.
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You will need a new remote. Nissan/Infiniti are notoriously outrageous on part prices though - check out Ebay.