Green led power light comes on,but screen is dark..picture periodacaly tries to come on,but instantly goes back to dark screen

Yes, it can be fixed but you have multiple problems. By the time you replace all that has to be you would be better off buying another disposable TV.

Sounds like back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced.

What is the brand name and model number to your TV? Provide more details, please. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy. Surf the site with patience.
http://electronicshelponline.blogspot.com/ Pull up older posts there.

Replace it with a new LCD Inverter, you can address the following issues:
Screen image, but the power light stays in
Dark display, but still readable
Flashing on and off of the screen between 1/2 to several seconds
The power indicator stays on, but no display and sound
Screen images, but LCD TV still has sound
Picture cycle on and off, as well as high-power LED lights
More information in: http://lcdinverter.info

Your shutter is stuck open. Remove the lens. Set to fireworks mode. May need to be in a dark room. When you press the shutter button tap the camera with an object that won't damage it. I used a rubber coated knife handle. Pull the battery and repeat. Tapping all around the camera. Hopefully it will break free. Then do some continuous shooting to loosen it up.

Hello,

I believe the power led button is still on while the screen goes dark, if yes, it means the picture board of your monitor is bad that is why it appears for a second and goes dark after that

Since the power led button is on, It means the picture board on your monitor is faulty that is why it appears for a second and goes dark.

The best thing for you to do now is to take the monitor to a local repairer or any service center within your vicinity to help with the replacement of the picture board because the fault is not something you can fix yourself in other to complicate issues.

Take care.

Issues with back light:
Please do not attempt to diagnose if no competent.
Do at your own risk.
Check for 24 Volts power to the inverter board
No Power---Check Power Supply
Power Present---
Verify status voltage 3v to 5v on inverter board harness (plug)
Replace Inverter Board

Check the Lamp if no picture, audio may be present. Screen is completely dark. Lamp LED flashes 2X every 5 seconds, Power LED flashes GREEN for 140 seconds then flashes RED.
Check the ballast if no picture, audio may be present. Screen is completely dark. Lamp LED flashes 3X every 5 seconds, Power LED flashes GREEN for 140 seconds then flashes RED.

I had a similar problem with my HANNSLounge 32", the screen switched on with green light but none of the front panel buttons worked (screen is black apart from showing the input source in the top left).
After powering off numerous times I tried starting up with a blank SD card in the reader and the tv cycled between red green and blue screens and then reset itself. (Some sort of firmware restore?) After which point I had a working screen again! (Will have to see how long it lasts for!)

If the power supply outputs are good! Then I would say the back light inverter is bad! If the screen stays black and does not come on.