I just picked up a 2001 xk8 with one key. Dealer found another key and fob and mailed it to me.

I just tried to use the fob to open the car, and it didn't work.
I tried the key in the door, and it didn't work.
I tried the key in the trunk, and it still didn't work.

My good key is currently 25 miles away at the in-laws.

Do you think my key fob battery is dead?
Do you think the car battery is dead?
Could the key not be programed properly?

Any info is appreciated.

 

Unless you or someone reprogrammed the key fob after you got it in the mail, it needs to be programmed (or rather the car needs to be taught to recognize the new fob). Did you compare the two keys to see if they were the same?

 

The known good key is at my in-laws until tomorrow night. 25 miles away.

 

And the "new" fob isn't really new. It came with the car, but the dealer forgot to give us both keys, and both fobs. Just got the 2nd set in the mail today.

 

It is the wrong key!
I compared it to my working key, and it is definitely different.

ugg.

 

Dealer probably sent you the wrong keys.