[ctuna]

This is a classic indication of no power to the FOB
You can pull the battery out of the Fob and it will do the same
thing.
When the battery gets low in the fob there is usually an low bat indication
on the instrument cluster don't know what happens when its dead.
But I have a dead key just for getting in and starting the car that you insert
in slot and it works as you describe.
Why don't you have more than one Fob two are suppose to come with the car.

If you say the key fob is brand new that would mean it did not come with the
car . When you got it was it programmed for the car at BMW or somewhere else?
If you just ordered the Fob did they as you what specification the car had although
they should know with the VIN number.
Also they have a key reader at most BMW service centers why don't you take it
in and see if they can read it.