Why are white dots multiplying on screen?

It looks like you have an LED and the light engine is malfunctioning. Soon they'll be multiplying.

Your 2 options are to get it to a repair shop but it'll cost around $1000 which you could just get a new (albeit possibly smaller) TV for that.

Another thing you could do is match the light chip (similar to the one below), which retails around $300 and replace it yourself following a video tutorial. Hope that helps.

It is not a user repairable fault. It can be repaired. Contact the authorized service center for Samsung.
If you wish to get some details; check the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/

projection tvs can display white dots from the dust that is on the reflector mirror your lamp shines the picture on before it is reflected onto the front screen of your tv, one must be very careful when cleaning this, may be worth a service man doing it for you

The white spots sound like the Optical Light engine has a bad display, they sometimes start with one or two and multiply.

The engine is about the most expensive part in the set, see attached photo of one

White dot for DLP Projector TV is not because of the light buy. It is caused by aging DLP chip ( DMD Chip.) Your TV DLP Part should be the following image:

Check the post how to place it diy

The dots are most likley the optical Block ( light Engine ). The not powering up issue could be numerous items , have you tried accessing the self diganosis feature with the power indicator blinking an error code?

If the white pixel dots start to multiply then Problem will be in the DMD board or the Light Engine.
PTS rebuilt boards/ Light Engines 1-800-844-7871
Samsung Parts 1-800-627-4368

if this is a DLP tv, white dots mean a light engine going bad. It will soon look like night stars in the sky.

This problems is the tv Projection Light Engine design flaw with it IC chip.These problems happen to many models of it DLP tvs Big Screen 60 and up.Mitsubishi,Samsung,Sony,Toshiba all used the same IC chip on their 60 and up on their DLP tvs Big Screen.Tries make deal with Mitsubishi help u split the cost of repair the tv Projection Light Engine by replacing the IC chip or replaced the entire Projection Light Engine system.This problems is not new,been going on for a few years.Many people when on Youtube **** about this problems with white dots showing up on their tvs screens and multiplying rapidly.

I'm guessing you have a Samsung rear projection tv. This is a common problem on them and can be repaired by having the DLP chip replaced. Samsung is covering the cost to repair tis problem on certain models. You can call 1-800-samsung to find out if it is covered and the nearest service center.