Promethean prm 20 - Promethean Board Promethean Prm-20a 720p Lcd Projector - Open Box

The Promethean PRM-35 is a projector, and it does not require any drivers to work with Windows 10.
To connect the PRM-35 to a Windows 10 computer, follow these steps:

1. Connect the projector to your computer using a VGA or HDMI cable.
2. Turn on the projector and set it to the correct input mode (VGA or HDMI).
3. On your computer, go to the "Display settings" and select "Extend desktop" or "Duplicate desktop".
4. Adjust the resolution and scaling settings to match the projector's native resolution.
5. Your computer's display should now appear on the projector.

If you are having trouble getting the projector to work with your computer, try using a different cable or input mode, and make sure the projector is set to the correct input.

find the remote ??

If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy Pull up older posts. Surf the site with patience.
http://electronicshelponline.blogspot.com/

open the case, and reseat the ribbon cable at both ends.
5 screws on the bottom and 3 screws inside the lamp housing to open the case. Be careful not to break the 2 plastic clips in the back.
Also check the micro switch on the lamp door is working correctly.

The white dots mean that the DLP chip has dead pixels. This can't be repaired by your average Joe or Josephine. The only time I ever "fixed" this problem (I fix these professionally), was when I happened to have another PRM-35 that had a bad power supply board. I was able to take the whole lens assembly (which includes the DLP chip) out of that machine and put it into the one with the little white dots. Check and see if it is still under warranty. If you have some extended plan, maybe you can get it replaced.

Not what you want to hear but this error means the lamp did not ignite. The most common problems I have had with projectors has always been the lamp itself, so if you have another or know someone with a good lamp try that first.

It's a 4ohm cabinet. Full 500W

Make sure projector is unplugged and cooled down, lamp can be very hot
Remove the cover over lamp area
There are 3 screws in lamp unit (they have little arrows that point to them even) or check against new lamp to make sure you take out the correct ones
Pull straight up, place new lamp in securely and screw back down (screws are attached to each lamp set)
Place cover back over lamp area and screw closed
Reset lamp hours by hooking up your computer to board
Get to lamp reset screen
Press down up left right arrows in sequence then press return button in middle

Did you check your cable? if the connection is bad the image will flicker in and out.

Check out this article from the Promethean KB
Why is my projector dim?