Panasonic dvd recorder model dmr-e55eb/ebl.

Question

panasonic dvd recorder model dmr-e55eb/ebl. played dvd,no problem - ejected dvd - green/blue colouring appeared on TV which disappeared when dvd recorder switched off. since then unable to play dvds. when dvd inserted machine continuously goes through 'reading disc' process. when pressing 'eject/open' no response. have to switch off recorder at mains and immediately press 'eject/open' to retrieve disc. tried various other discs - same problem. any ideas/suggestions. any help most appreciated. many thanks