I have a Panasonic TC-55LE54 screen freezes about every 5 seconds

Hi Chris! It could be one of 4 things causing no backlights, LED driver, main, and power board, also it's possible the actual backlights have failed however Panasonic sets haven't seen this issue like most other brands have. Do you have a multi meter and can get some voltage readings? With out them it's a guessing game as to what board or boards are bad

Main board would be where I'd start

It almost sounds like a capacitor issue. Any and all televisions have quite a few of these and any of them could be the culprit.

Could be a bad connection that disconnects when heat in the system causes it to expand. Take to a pro or call manufacturer, they might have a recall or free repair available.

Main digital board should be troubleshooted. If you are not familiar with electronics, do not attempt to repair. Whether you suffer fatal electrical shock! Instead, contact any experienced service technician, or the nearest service center

TC-55LE54 use the digital audio out

Google the model number with 3 blinks or error codes and you should find it.

Rule out any loose contacts in power outlet, RC Jack, cables and connectors. The problem described by you calls for opening the back cover and further investigation, which should only be done by a qualified service technician.

David, what did you find out. I have the exact same problem as of two days ago.