How to change remote key battery?

the easy way to see if your battery is weak is when you press the boot button and nothing happen fast, i find this is the first sign for battery change.
strange but i had a key with no battery in for longer than 10 sec and when the battery was replaced it worked fine??
the other thing that our boxsters do is if you do not use your car for a few days the locking system goes into an energy saving mode and you will not be able to open you door with the remote but will have to use the actual key and turn the ignition quickly or the alarm will sound

[Tool Pants]

I have had the battery out of the remote a lot longer than 10 seconds and it did not lose the programming.

[Z4oldie]

Hi all
First post on here in response to your helping me with my non functioning key fob

Removed and replaced dead battery and didnt need to re-program

2004 Boxster 2.7