I must say I agree with the others saying that you can't get enough hair in the ring to safely secure the nano tip.
Don't feel bad you haven't done anything wrong, I had a client that did the exact same thing with the la weave method (how I know) her hair was so very thin on the ends before the application, due to never ever having it cut, because of this I had no reason to touch her natural hair ie. Cutting and blending, she had them in for under three weeks, and was moaning so I asked her to come and see me so I can look at it so check it over, booked her in three separate appointments (1 hour and a half each incase I needed to refit the whole thing) every single one she never turned up and never let me know she wasn't coming, then finally told me her her bf had taken them out with his house hold pliers and tried to tell me her hair was now "non existent"
If they've been removed by a unprofessional whether that is her hairdresser or her boyfriend, it voids all warranty, simple as
Some people will never ever be happy!!!