If also you have problem with your old Adonit Dash 3 Stylus and you want repair it, you are in the correct post.
In particular I have problem with the battery life, but in this post I try to explain how to umount Adonit Dash 3 to repair any problems.
Disassemble the pen
To disassemble the pen you must remove the tip, and after with a plier you can unscrew the other part (If you want to preserve the component you can cover it with a insulating tape).
After that you can rip off the stylus, that will break the button connections.
Infact after that the button can be pushed out with a toothpick for sausages or somethink similar.
If your problems are not in the stylus you can see this video that show how to repair the charger.
I want to replace the battery but I do not do It now, I also do not find better way to umount the stylus, to broke the button connections seams mandatory.
If you have better idea or you use different tecqniques please comment and help the community.
Repair if you can and save the planet!