Leather mask radar

Hi I have Yamaha PSR-550, why LCD displays nothing? - yamaha psr 550 replacement floppy drive

As of 2 days each time I return my keyboard with LCD screen displays in 2 minutes, even if nothing shows inside and out, but if I go to 3 or 4 hours late, if I go back and see all the options, and then disappear 2mins to change, is the problem? But if the strike affects work, with the exception of the piano keys, I can not every mixture, etc., I can help someone to know exactly the problem?

Thank you for your help in advance ...