Chuwi Hi10 X stylus stops working

I bought my Chuwi Hi10 X with stylus about 3 months ago. I’ve used it almost every day, for a couple of hours a day, with extensive use of the stylus (for studying).
It worked great until a couple of days ago: now, if I use it for more than like half an hour it starts not to register anything, at first intermittently and after a bit it stops working altogether.
I tried to charge it up, but that doesn’t seem to be the issue.
What do you think could be the problem?