Hi and welcome to the site, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, have you tried unplugging but longer, extended period of time? ...and then plug back in but to a different outlet?
Yes please. The idea is to dissipate residual / internal voltages to simulate a soft reset.
This is the only easy user doable try as all others would be to the internal circuitry.
Sorry to hear of this.
F76 is an error code indicative of an internal hardware issue.
Please click HERE.
Are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even a soldering iron?
Would you be comfortable opening the Panasonic, working inside with electronic components? ...in some instances with the unit LIVE?
Please click HERE and HERE for the multi-meter and soldering iron respectively.
First test would be for the different voltages specified on the first link.
Post back with clear picture(s) of the power supply circuit. Click HERE.
Good luck and thank you too for the opportunity to share the information.