It means that there's a misaligned disk inside. You need to
1. Unplug it and shake it side-to-side.
2. Then turn it on and press the open/close.
3. If it doesn't open, goto step 1.
4. When it opens, get the disks out, use disk exchange to try to get them all out.
5. Turn it off, unplug it, shake it again and make sure that there isn't another loose disk, if there is, then open it and get it out.
This is a known flaw in certain Panasonic DVD changers. Good luck
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