I managed to pop out the first cap with the hole but i'm not sure what to do next. do you have pics to detail the 2nd part and the drilling please? thx
I don't have any pics, but it's pretty simple. I actually removed the second cap with the drill. If you use a small bit (1/4" or slightly less) and drill down on the second cap the drill will cause it to break loose and when you pull the drill bit out, that little round piece should be attached to the drill bit. Once the second circular piece is removed you will be able to see the bottom of the rectangular area that holds the fiber.
From here, it was just a matter of pushing the drill bit down
through that plastic and widening the hole a little (though as Martha pointed out, this may not be necessary)
I used linesman pliers to hold the cart, but any set of pliers that can grip the cart will do. It will scuff the cart up, so use a towel or piece of rubber sheeting between the cart and pliers if you want your cart to stay pretty.
In another
thread, someone else mentioned using an exacto knife to cut out part of the rectangular area... which seemed too skillful for me

Easier for me to ram a drill bit down
through there until it's hollow all the way through.
If you don't want to use the drill method, straighten a paperclip (or use something similar) push it through the hole and pop that little guy out.