Hi,
If the small particles are glass, then there is a problem.
If maybe some kind of glue, then one needs to carefully clean it may be using a small vacuum device with batteries to extract any remnants inside.
Then screw it back carefully after cleaning seeing how many start positions there are.
The scope is no longer waterproof if it was before.
Alternatively, if there is no glass damage, then ask East Coast binoculars whether he can repair it and purge it with nitrogen or argon or whatever is needed to make it waterproof.
Also, it may need realignment.
Maybe £100 cost?
So, are the small particles glass debris or something else?
I think you just applied too much force and should have held the top of the tube when unscrewing the cap.
I don't suppose you have house contents accidental damage insurance.
But even if you have there may be an excess.
So, ask East Coast Binoculars for a quote, and if he won't repair it, who might.
You could ask Richard at Action Optics, Southampton if he might have a go.
Regards,
B.