I ran into the same issue as some of the other folks here.
The TV would turn on, we'd see the bright white/blue Olevia logo, then the screen goes DARK, but you can see a shadow of movement.
The diagnosis above was CORRECT, it was not the main system board, it was an inverter board, specifically inverter board #2 on the top left as viewing the TV from the rear with back panel removed.
I was able to order inverter boards from ShopJimmy.com, cost was a paltry $70 each plus shipping. I ordered (4) boards total, a #1, #2, #3, and #4, as I didn't know which board was bad, but thought it might be #2 as with another user who posted here. (There are 6 boards total, but only 4 unique part numbers, a couple of the boards are used twice).
I plan to return the other 3 boards to ShopJimmy and pay the 30% restocking fee, which seems extremely reasonable to me, as the entire TV was repaired for under $200 with the cost of the board, express shipping, and the restocking fee.
For most folks with this exact same problem I'd recommend just picking up a #2 board, and if that doesn't do the trick, order the others. I just didn't want to take a chance as I was getting wife 'agro'. My marriage is worth $300. ;]
Now I'll give a rundown of the actual repair procedure. Note: I'm a computer technician/company owner with 27 years of experience in the field with repairing every type of computer under the sun. From old school Apple IIe computers, to 286s, Mac classics, PDP-11/70s, to custom built gaming rigs.
That being said, any monkey with a screwdriver and patience could pull this off. You'll want to wear a 'static strap' for safety so you don't fry any components inside the TV and cause things to get worse, and of course touch metal in the case to discharge any static as often as you remember.
The tough part for me was that the TV is 240lbs, was sitting on top of a 4' tall dresser, and I didn't have anyone to help me move it. After a long night of sitting there mulling it over (watching TV isn't as fun when it's broken), I decided to drag one of my Klipsch 30s up from the downstairs home theater (133" projection), and then pivot the TV 90 degrees to the side so I could safely access the back panel.
The height of the Klipsch speaker was about 6" higher, but a couple nearly useless phone books found their calling in life, if only for about 24 hours.
I had no idea how to get this puppy apart beyond someone mentioning the speakers would have to be removed, and about 50 screws. That was pretty accurate actually.
First step is to (DUH!) unplug it from power completely, unplug any video/audio cables (but mark where they were connected for ease of reconnection later!), etc.
Now, scrounge up about 8 containers, or maybe an egg carton, so you can deposit the screws in labeled buckets so you'll know where they came from.
From here you can remove the panel for the main board. It's got maybe 10 screws holding it in, plus, important, you must remove the screws holding the RCA jacks and other inputs/outputs. Miss this bit and you won't be getting that panel off. If you're only replacing the main board (as many people have had to do), you're pretty much done. Remove and replace the old with the new, and button her back up. If you're doing the inverter, buckle down and get ready to work a bit.
Next up, remove the speakers. You'll find 6 screws with rubber grommets holding each one to the back panel of the TV, plus 3 more along the bottom.
This will loosen the speaker, it can then gently be rocked away from the TV, but will still be connected. The wire actually has a releasable connector, but it's inside the TV. You can gently pull on the speaker wire until the connector comes through the hard plastic grommet, and disconnect. I didn't notice any difference between the right and left speakers, but you might want to mark them.
Then you can start getting to work on those '50' or so screws, there are 6 big ones in the top/center of the back panel, then a whole load around the edges. Remove carefully, don't strip any, and place in your marked containers.
After that the back panel should be pretty loose, and you should be able to gently release it from the back of the TV (once you've found all the screws you missed!)
Once you get the rear panel off, find a way to store it SAFELY. Maybe lay it flat, hang it from the handgrips, etc. Don't just put it on it's side facing upwards like I did, as it must have warped just a bit making some screws tough to put back in later.
Ok, you've got the back off, you can start attacking the inverter boards. I started with lower right (#4 I think), replaced it, no effect. I reversed my work and put the original #4 back in for now. Then I found a #2 on the lower right, and as someone had mentioned it being the #2 board for them, I tried this one next.
Ok, popped the original mid right #2 back in, and found the other #2, which is on the top left. Popped that in, and BAM, nothing.
WTF? Seriously? I went around to the front of the TV, and turned it on and off a few times as I had previously, same thing. DAMN. The Olevia logo comes up, the the screen goes black and a message comes up in the bottom left 'No Input'.
Damn. Damn Damn. I thought it'd be that #2 board. *WAIT*!!!! HOLD THE TRAIN!!! It didn't say 'No Input' before!!! I'd forgotten to reconnect the HDMI cables after my test, as they directly interfere with the replacement of the top/left #2 board.
Plugged them in, and JACKPOT!!!! KING OF THE LAB!!! KING OF THE LAB!!!! (Reference to the excellent TV show 'Bones').
I was utterly filled with a glow of satisfaction at being able to do this repair myself. I know, as a technician I should be able to, but manhandling a 240lb TV around alone isn't easy, and I was really working in the dark without any real instructions or directions.
Actually, no, I wasn't working in the dark, I had a couple mini-lamps which were *EXTREMELY* useful for finding those screws I failed to remove.
Ok, enough patting myself on the back, the actual instructions for removing the inverter boards is pretty trivial. There's 6 screws holding each one to the TV, 4 of those screws hold the metal cage protecting the inverter board in addition to mounting it to the TV. You can remove all of the cage screws and leave at least one screw mounting it to the TV while you disconnect the cables.
I think there were about 8 cables along the side, feeding the backlights. If you gently push down with a thumbnail in the top/center of the connector, it will release quite easily. (Took me a few mins to figure this out). There's also a ribbon connector connecting this inverter board to the one next to it, along with a longer cable connecting the inverter board to the main control board. They're all pretty easy to remove and replace.
From there you just reassemble in the reverse order, it can be a bit tricky getting the back panel on, but you can attach it along the top on one side loosely, then get the screws in on the top other side loosely, and from there you can work down the sides/top/around the edges to get it locked down properly.
That's about it kids, enjoy your fantastic TV for a few more years, with a total repair cost of under $100 (plus labor).
Be proud of what you've done, your wife will brag to her friends and co-workers about your achievement.
I've got some pictures I snapped, and will try to get them uploaded later. A visual reference to the above guide makes things much easier.
Part numbers from ShopJimmy:
Sharp RDENC2244TPZZ Backlight Inverter 2 sj-RDENC2244TPZZ 1 $ 69.95
Sharp RDENC2243TPZZ Backlight Inverter 1 sj-RDENC2243TPZZ 1 $ 69.95
Sharp RDENC2246TPZZ Backlight Inverter 4 sj-RDENC2246TPZZ 1 $ 69.95
Sharp RDENC2245TPZZ Backlight Inverter 3 sj-RDENC2245TPZZ 1 $ 69.95