Used 2006 X5, dead remote lock/unlock keys

I just purchased a 2006 X5 from cash only used car lot. Both the keys lock/unlock remote do not work. I was looking online how to replace the batteries and came across this:

[https://xoutpost.com/bmw-sav-forums/x5-e53-forum/63258-diy-replacing-battery-key-fob.html](https://xoutpost.com/bmw-sav-forums/x5-e53-forum/63258-diy-replacing-battery-key-fob.html)

Does anyone know if its possible to do this if both keys are dead, the guide in the forum indicates that it might be necessary to have a working one to program the dead one after battery replacement?

Or is there any other advise on this?