Turned on the tv, heard sizzling sound and it immediately shut itself off. Won't turn on now. It had been turning itself off periodically now and then for the last couple of weeks with no noise and then would turn back on after a few seconds. Last night it would not turn on, just the sizzling sound and shut off within a couple of seconds.

SOURCE: TV will not turn on

Probably needs a new HV Splitter block, they are very difficult to replace and can usually be accessed thru the front behind the speaker grill and behind convergence board.

SOURCE: RCA D52W23 has shut off twice within the last week..

Try a power drain and monitor if the TV continues to do this or not:
1. Unplug the product's power cable so the device is not grounded to the house. 2. Press and HOLD the product's own power button for 1 minute to drain the capacitors. 3. Plug the product back into a wall outlet and try to turn it on.
Note: This procedure works with battery operated devices as well so remove the batteries and hold down it's power button.  Electricity can remain in capacitors and on circuit boards enough to prevent normal functionality. By clearing the residue electricity, your product will have a fresh start and many times this will resolve a buggy or non-responsive device that appears to be dead.
If this doesn't resolve the issue, it's possible the power supply is on it's last legs.

SOURCE: My RCA Bigscreen HDTV will not turn on.

If this is similar to the d52w20 then I almost garantee you need to replace a capacitor. You can check to make sure that's what you need by unplugging the tv, taking off the back cover and feeling the top of 3 capacitors. On my d52w20, CP150 (rated at 2200uf 16V) was blown and the top was bulged out. You should also check CP120 and CP114 to see if either are blown. I don't have a clear picture of where it's located, but I have a picture of what you should see after you take off the back cover.

http://i265.photobucket.com/albums/ii209/fillmore85welder/KodakMoment003-1.jpg

In the middle of the picture you see an aluminum heatsink in the shape of a 'C' with the opening facing away from you. That is where CP150 is located. CP120 and CP114 should be located nearby, but if you can feel a bulge on any of the tops of those 3 capacitors replacing them should fix your problem. Replace the existing capacitors with a higher voltage rating of either 25v or 35v.

"4 capacitors on the power/deflection board. CP110 220uf 200v. CP120 220uf 35 Volts. CP114 220uf 35 volts. CP150 2200 16 volt. also check entire delfection board for cold solder especially around flyback. bad connections here can cause problems like some of the fp fuses blowing and cutting off convergence supply"

SOURCE: I go to turn it on and it sizzles and shuts itself off.

you need to look on the left bored in the back off the tv it must likely that a part it loses form the bored and need to be sorted back on the bored that what happen to me easy fix just be careful with the sorting iron it get every hot lol

SOURCE: My RCA 52 inch rear

Replaced the high voltage transformer. It is arching.