Facing TV Problems? Ask a TV Technician.
Hi and welcome to JustAnswer, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, and on "...cannot get the energy saving mode off..." even using the ENERGY button on the remote?
Still, no backlights can be seen from the back of the TV? ...through ventilation holes?
The 42LS4600 is a LED type . In most versions, the backlightcan be seen looking from behind through the ventilation holes.
Still, consider a test (if have not been done). Power on the TV and set to a program/channel. If at all possible, darken the room where the TV is. Wait for about 5 minutes or more. Shine a flashlight at an angle (not directly) and nearly but not touching the screen where the volume level / menu display is usually seen.
Press the VOL UP/DOWN or MENU button and note if a dark/ghostly image of the volume level or MENU could be seen.
Post back results.
The above is a test to determine if it is a back lighting issue.
The above flashlight test would confirm the backlight issue; i.e. an internal hardware concern.
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 perhaps a soldering iron)?
...or would a LINK to an independent repair shop serve your need?
Please try unplugging the TV for an extended period of time.
The idea is to simulate a soft RESET and dissipate residual power.
Then while still unplugged, press and HOLD the ▼ and + buttons on the TV itself while plugging back in BUT preferably into a different outlet.
Please post back results / observations of the above once tried.
This reset is both a test and a try of a fix.
May have to be done a number of times.
This is very critical - a reset however would not be corrective of an internal hardware concern; but it would be confirmed. In some instances, it may even expose/cause other issues.