Recently purchased Panasonic SC-PM54 - virtually new - stored some years but not been used. First put 1 disc in to test. Played OK; but now CD drawer will not open, will not do anything (ignores "Demo" "check CD" - constantly flashes "change" but will do nothing. Cassette function OK. I did momentarily use the remote from another system - does a couple of functions. What could the problem be? It is a beautiful little system, and was all 100% when I put one disc in to try it out.