The same thing happened to ours, and we could not get all of the film off either. We just ran the machine as usual, even though a bit of film was still stuck on. Eventually, it stuck to the other film as it was running through, and now it’s no longer there. I am not a professional, so not sure if this is the best solution, but it worked for us.
Sometimes you can remove the back panel by unscrewing the screws that hold it in place, then you just have to turn on the machine and try to carefully tug the film free. If that doesn't work, you might have to call a technician. Sorry!
