Troubleshoot Screen is flashing only solid colors, not picture

Sounds like fault with the main digital board. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts.
https://elektrotricks.blogspot.com/
https://electronicshelponline.blogspot.com/
faults & possible causes to LCD screen are given with illustrations. You can get an idea about the fault to an extent.

Take it to a TV repair-man TVs are much like PCs these days and it sounds like you need to re-flash the BIOS

Disconnect from computer and try it on another.
might be a video card issue, disconnexion will show if this is the problem. Does it do this when the computor is off?
If it is not a computer issue then try resetting to factory default.
It might be that the screen is going but this is usually evidenced by loss of picture or darkening rather than vari-colour lines
please amend and resubmit query

If your LCD TV or monitor has stopped working, or is displaying one of the following symptoms, then it's a candidate for some new capacitors
- Flickering screen
- Screen image disappears after several seconds
- Dim screen
- Slow start
- Power LED on, but no picture
- Unusual colors and/or lines
The primary cause of LCD TV and monitor failure is caused by faulty capacitors. You can examine the capacitors in your LCD TV or monitor and actually see if they are bad.
If they appear bulged on top, then they need to be replaced.
New capacitors will solve a host of problems in LCD monitors and TV's and will extend the life of your monitor or TV by several years.
Check the cables, connectors and connections.
Take it to a repair shop.
https://www.youtube.com/watch?v=TR2iWN6b-LY
LCD TV Repair No Power Power Supply Common Symptoms Solutions How to...

Its a Good Possibilty that its the New Color Wheel causing this,if the colors are not complete on the color wheel then that will be why you are seeing shadow on right hand side of screen.
I know I ordered color wheel for mine and had to send it back,it did the same thing.
I compared it to the old color wheel and the new one did not have Solid colors on it.

Can you see picture behind the shadow? or is it shadow and no picture?

If you can get the tv to display the blue blackground(usually happens when there is no antenna or cable feed to tv) check to see if the whole screen is a solid blue, if it shows discolored areas around the screen then you might have to "demag" the screen. See if you can rent a demad coil from a tv shop and with tv on turn the coil in circular movements all over the front of screen till blue is solid.good luck!

TRY USING THE COLOR CONVERSION OPTION ,,ITLL FIX THE COLOR

There is a component failure on the board inside the display. Since you did not post the model number that is all that I can tell you.

I had a similar problem on a different monitor and fixed the green sparkles by selecting a lower refresh rate.

Sorry time for a new monitor you might open it up and look at the capacitors and see if any need to be replaced the bad ones will be domed on top normal is completely flat