At first glance, I think you may have had the filament break inside one of the PTFE tubes.
The AMS is very easy to pop apart, and the tubes disconnect inside very easily, you can usually see it through the tube.
Here’s the procedure:
https://wiki.bambulab.com/en/x1/troubleshooting/filament-breaks-in-path
The videos are short and well done.
Oh yes - usually I’ve found that if a filament is fragile enough to break in the tubes or while loading / unloading it means the filament has absorbed moisture and needs drying. I always flex a filament with my fingers before loading and if it is brittle I go dry it.