Question How do I unscrew the bottom part of my HP pen?

[LTL428]

So I have the HP elitebook 2740p, and I know it's an old laptop, but I bought it just to have a chunky secondary device with a touchscreen. I'm not sure if mine has a finger touch digitize screen, but all models at least support touch with the pen. I noticed it wasn't working, and then remembered the pen needed a battery, when I tried to remove the bottom part of the pen (Which had a crease as if you could unscrew it) it kind of clicked, and then stopped. I'm pretty sure you can unscrew it, but I don't know how to. If anyone knows or at least could find something that would help me, that would be awesome. Thanks.

 

[Ralston18]

FYI:

http://h10032.www1.hp.com/ctg/Manual/c02272381

The pen as is shown on physically numbered Page 43?

I found the following video link:

View: https://www.youtube.com/watch?v=WTQKmThbAP4


Not an exact match but may lead you to a more applicable link.

 

[LTL428]

FYI:

http://h10032.www1.hp.com/ctg/Manual/c02272381

The pen as is shown on physically numbered Page 43?

I found the following video link:

View: https://www.youtube.com/watch?v=WTQKmThbAP4


Not an exact match but may lead you to a more applicable link.

This did not help, but thank you very much for your time to help