I have no experience with this
mod, but if I remember correctly it is an ego style designed to take an 18650.
You can try turning it off and back on using that five click function.
If that doesn't work, I'm going to guess that it's gone. It's really not meant to be user serviceable.
Maybe someone that has more experience with that model can chime in.
I don't know if that model has reverse polarity protection.