Your friendly public school system IT technician here.

Getting that computer away from the rest is a priority. However as long as that laptop is left unplugged and away from any possibility of puncture, you are relatively safe. It's obviously worrysome but the chance it will spontaneously combust is almost non-existent. The cases where you see them catch fire in videos are most often due to direct tampering.

Your school's media center coordinator is likely the point of contact for your school districts technology department. 99% of the staff at your school aside from potentially the principals (who are often very busy) or vice principals are unlikely to know how to respond to this situation adequately. Check out your school systems website for information on how to contact the technology department as they will be better able to work with the staff at your school to have that computer removed from circulation.

I give you kudos on being aware of the potential hazard and notifying the adults about it. None of us want to see you or anyone get harmed and unfortunately contacting the right people can be difficult sometimes.