My wacom bamboo fun pen (CTE450) suddenly broke down, so instead of purchasing a new one right away which wasn't cheap; I thought to open it first and see what went wrong and hopefully repair it. The eraser part still works just not the nib.
If you have a wacom pen that doesn't work after you dropped it, a likely reason could be the copper coil has come apart. I did not drop the pen since it suddenly stopped working after I came back from a break and found it wet. I googled around and found a great post that helped me and you should check it out if you suspect the internal parts have broken:
Use a small screwdriver to pry under the lower blue button. The first snap should come out but do not yank the whole blue part out just yet, as the second snap holding down the button will break off. Instead after releasing the first snap, slide the blue button downwards and it should come right off.
Like this. Press it down slightly to release the catch and slide towards the right. You will have a whole button without broken bits this way.
Next would be the very annoying part. Pull the pen apart in as straight as you can. Do not bend the pen while separating the pieces as you don't want to damage the circuit board hidden inside. This is a pain to do as it requires some force since a few notches are holding the plastic together. If you can't get it apart, you need to use more strength, just make sure it doesn't fly! I used a flat nosed pliers at first to get the initial gap going and it damaged the corners of the plastic a little bit. Took me a good 15 mins and a guy to get it apart.
If you really have problems getting it apart, what worked also was a pair of round-nosed pliers (from my jewellery crafting), I grasped the round nose pliers between the parts, after I had about 2mm pried apart with my bare hands (took some strength for me to do that). Then sort of squeeze the pliers down with its fatter section to get the parting enlarged.
The circuit board is still attached to the front part of the pen so the next step will be to remove that button holding the circuit board in place. Be very careful with the eraser part since it is exposed because those copper coils are part of the ferromagnetic core that act as the sensors with the tablet. Also handle the circuit board by its sides.
You can remove the plastic nib now or before starting this project. Just use a pair of scissors and don't use any force to grab it with the blades and pull it out from the mouth. Pliers don't work as well because it slips.
Getting this button off is the next pain. First I don't want to break the plastic, second it's tightly snapped to the circuit board.
I inched a tiny screwdriver (the kinds for watches & jewellery) underneath the button (from the surface of the shell) and pried it out on its sides just get that thing out of there, but in doing so damaged a little of the plastic surface. Two snaps hold it in place. Whatever it is, it requires some force and you know it's out when you hear a snap sound (hopefully you haven't broken anything).
I examined the whole thing and found nothing wet or broken with it. Gave the outer shell a cleaning anyway since there's dust and gunk around the buttons, and used a dry, clean cotton swab (q-tip) and very gently wipe the circuit board that might have been affected by moisture.
The copper coils are intact so it wasn't a physical damage that was causing the pen to break.
Usually when you drop the pen the delicate copper coil may have come off its solder to the circuit board (which you resolder back) or it has broken (which can be mended by super glue - just see the link at the beginning of the post). In my case it was probably moisture or it just needed a good kick in the ass for it to get working again.
If you spilled cola or something other than plain water I think you might need to actually clean the thing with distilled water to wash off any residue and let it dry completely before testing it again.
Reassembling took a few seconds and the thing works as it did before!
If the cursor works again after you've cleaned it (test before fully reassembling) but the button clicks are doing their own strange commands all over the screen, try going to the Bamboo settings and under 'Pen' tab, click to Mouse mode, test, and then back to Pen mode.