DVP5990 Tray randomly ejects

Tray randomly (and frequently) opens and closes. Even when the player is turned off, so i have to unplug it when not in use. Please let me know if there is an easy fix, as I’m not looking to order parts.

If not, is it possible to disable to the tray completely, since the USB port works fine. It’d be nice if it went straight to reading the USB port instead of looking for a disc, and then I’d be able to leave it plugged in as well.

Thanks!