Blank screen, looks black from the front, but appears blue when looking at it from the side.

Just change everything, or take this advice.

https://www.fixya.com/support/r29790007-repairing_own_television

..

Sounds like the backlight is not working. Check the LED backlight driver board.

I would scrap the TV, you have already wasted money.

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.

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://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. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Im having similar problem and with my limited knowledge of lcd tvs and the voltages ALL being good except the pwr on or sw on voltage from the main board to the power supply which tells it to switch everything on Im guessing that something is going wrong on the main board. In the condition where it freezes it (the power on V) which switches everything on i get varied voltages such as 2.5 or 3 or (the normal 5v) and then when nothing powers up (blank screen) i read 0v on pwr on voltage but all my other voltages are corect (24v to inverter, 12 v to main board, 5v, etc.) Im guessing from researching this is that there is in improper voltage somewhere in the main board circuit. I have been unable to find it so i may order another board and post back.

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. Pull up older posts.
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.

There are two places to look for the problems, the backlight inverter board and the power supply. Look at the power supply first since it is easier to get to, look for burnt parts, bad capacitors, etc.
http://en.wikipedia.org/wiki/Capacitor_plague
Please post back what you find.

If black bands are appearing on all documents your scanning then yes you have to get a new scanner. Main board inside of the scanner is going bad and you can't buy spare parts for scanners.

The other thing you can check just to be sure. When the scanner is scanning the light will go all the way to one side and then move all the way to the other side. Look at the light and see if it stays on the whole way when its moving from side to to side, if it does then the main board is bad, if it doesn't then it could be a faulty scanner light and that you maybe able to replace depending on how old the scanner is. Best thing at that point would be to google your scanner and see if that spare lamp is available.

if the blue light flashes 4 times Main power led to on/off switch is crushed and not enough power gets through.
you have disassemble the camera.
I would think first before tring this.
Remove 3 screws on bottom, 1 in battery compartment, and 1 at very top of usb flap (look good).
Now slide the side piece starting at the usb flap then apply pressure to top and away from unit.
now look for 1 silver and three black screws (facing back and front, look good).
See the big red wire leading to main on off switch if it crushed thats the problem.
I replaced it with a longer piece of wire.
Remember to replace battery door first if it fell off during process.
*TEST NOTE: You can place batteries in and place a penny across the bottom to test before you put it back together.