The "obvious" questions had to be asked. I'm running out of ideas.
Is it a powered glider?
If so it may have a safety switch of some sort. If there is an ESC it probably has a specific arming sequence you have to follow.
If it isn't one of those things, I am stumped. Hopefully other ideas will come. Is there a flying club or good gobby shop near you where you can get hands on assistance?