here is link for a board on epay $32.95 they go as high as $ 75.00 there Shopjimmy.com is out of them.
Board number is K02P133.00 made in China by Ampower Technology for Samsung as you already know obviously outsourced a lot of companies do that . Ampower Technology is a holding company ( hope that wasn't made on somebodys kitchen table over there) just kidding.
Supply chains aren't always that transparent.
I Googled the part # it matches up with your set model #
Google has quite a few links looks like that board is a power supply and backlight inverter combined on one board replacing it kills 2 birds with one stone so to speak so that's good.
Not knowing what the particular jumpers mentioned previously on the other sets do or exactly what circuit it is in makes it a little tough to see if there is an equivalent jumper on this board . I suspect it goes from a floating ground (neg volt rail ) to a chassis ground perhaps might be part of a soft start circuit that develops a capacitor or voltage regulator fault and shuts the board down hard to say only can guess .
Seems strange that the tech you went to mentioned a "screen control board" unusual terminology that would be more of a TCON board maybe he was thinking.
Your picture flashlighting would be the power or backlight inverter board by symptom which repairing / replacing this board should fix .
This is easily verified by voltage measurements with a DVM. duplicate symptom look for absent voltage .
You only have 3 outputs on a combined board two 5.3v rails , a 13 volt rail and a 700 volt rail the 5.3v rails probably go to the logic/tuner board and switch control board/remote receiver ,The 13 volt probably to the TCON board and the 700V rail to the lcd backlight . you can get a DVM for ~20.00 or less but if you can get a working board cheap
that;s another solution some sellers guarantee the boards power boards are the easiest to test. That board seems to be hard to find
component level repair of the board by a tech might be an option . LCD alternatives or some one may be able to repair that one.
You mentioned when you hit it the picture returns that may indicate a faulty solder joint maybe the board should be removed and all the solder joints and traces carefully inspected and re flowed as needed . Surprised the tech did not suggest that if he knew that hitting it could make it work. That would be the first thing I would look for in that circumstance aside from obviously failed parts . I wonder if he took a meter to the power supply ?
. Lead free solder they use now is not as good as the old stuff.
here is a google page on the board