visit the official panasonic website, to download the firmware, and see if it is possible to load it with the tv off .... greetings.
https://translate.googleusercontent.com/translate_c?depth=1&hl=en&prev=search&rurl=translate.google.com.mx&sl=en&sp=nmt4&u=http://av.jpn.support.panasonic.com/support/global/ cs / tv / download / fw / index.html & usg = ALkJrhi4bS9I3CBnwoKmWwFv_V4rhTMdGA