Sharp LC-50N7000U logo comes on then black screen, what needs replaced?

You will need to preform a power drain cycle on your TV here.Unplug your TV from the power source.Press and hold the power button for about 10 to 30 seconds.This will help drain all of the TVs residual power. Now plug the TV back into the power sources.

I'd start with a replacement main board

This would mean that either a CABLE BOX, SAT BOX, COAX CABLE, HDMI CABLE, ETC may not be working properly, something is loose, or needs reset.
-Reset ALL components by unplugging them for 5 minutes including the TV.
-Be sure all COAX CABLES and HDMI CABLES are tight and properly connected.
-If you CAN pull up the TV MENU when you have the black screen, update your TV’s firmware to be sure your TV is up to date and rule out the TV as the problem.
NOTE: If the TV now works and there is no BLACK SCREEN, the issue was either a loose cable, old TV firmware, or a component that needed to be reset and the issue is now resolved.

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

Sharp TV - Flashing OPC & Power Lights - YouTube

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https://www.youtube.com/watch?v=BH1OcQ6dIEE
Jul 1, 2011 - Uploaded by Tweetssun
Sharp Aquos TV flashing a OPC & Power Lights in a pattern of 3 flashes, ... Sharp Aquos LC-32D44 - One blink lamp error - Nopicture or sound - Diagnosis ... Repairing Flat Screen TV - Blacked out with blinking red light ...Missing: 32dv22u

Sharp lcd tv power button flashing - HDTV - Streaming Video & TVs ...

www.tomsguide.com/forum/54708-4-sharp-power-button-flashing

Feb 8, 2012 - 7 posts - ‎3 authors
We have owned a Sharp 32" LCD TV for about two years. ... However a quick Bing search shows that the blinking green light usually means a bad power board, which seems ... No picture, no sound, just a black screen and two blinking green ... a cable surge block on the coax where it comes into the house. Sharp lcd tv power button flashing - Digital TV
19 posts
Oct 14, 2012
Sharp hd tv blinking power no picture - Digital TV
2 posts
Jan 7, 2012
More results from www.tomsguide.com
Missing: 32dv22u

Sharp Aquos LC 42DH77: Inverter, Backlight, Power and ...

www.normsweb.com/tektips/42dh77.shtml

the motherboard needs replaced, due to the onboard voltage regulator is out.

I do have a work around that I have used on this model for the past3 years. if the sceen goes black. Turn off the tv. Grab the upper left and right hand corners of the tv with your hands. Flex the tv slightly back and forth. then turn it back on. my will usually run for hours after I do this. I do this 4 times a week. I works 100% if the time for me. Sharp lost a customer. good luck.

The Sharp TV model LC32D40U / 41U "Black Screen problem" is a very well known issue. The inverter is losing ground contact which will prevent the back-light from staying on. The solution is to re-tighten six screws on the inverter board. You also would want to clean the copper contacts on then bottom of the inverter where the screws go through. Access to the inverter board will require some disassembly. Plan on taking at least three hours to repair. See the photo for the location of the screws. Use some "blue" locktight" on these six screws. There is actually a Sharp Technical Service Bulletin that describes these screws. Sharp wants you to replace these screws with a newer version. They cost at least $2.50 each! I think my method will work just as good using the "Locktight"

this is either a power problem or the screen needs re-gasing