I have an NEC VT470. The projector shut down after the lamp finished. When I replaced the lamp and pressed the start button, the projector does not come back on.

steady orange means projector in standby mode
red light 6 times is a lamp error.
either the lamp is old and wont start up or the ballast power pcb is not working.
can you hear the sparking of the high voltage trying to strike the lamp.
if you can then the lamp may be dodgy.
can you borrow one to test it out

If you replaced the lamp already, chances are the ballast is defective. When you power on the projector with the power button you should see a flicker of light in the lens, or an electrical sound. If you don't you ballast is bad.

I had the same issue, what I figured out was that I never removed the lamp door correctly, causing a small plastic piece to break off. To see if this is also your problem, inspect the back of the lamp door, top right corner, if it seems a rectangular plastic piece is missing, thats the problem. It presses in a small button nearby the lamp to let the projector know it's safe to power on.

I've attached an image to help out.

change the lamp even if the old lamp

use original nec remote contro

l6. After you install a new lamp, select the lamp Usage icon and press and hold
the "Power On" button on the remote control for ten seconds to reset the
lamp time clock to zero.
NOTE: If resetting the lamp clock back to zero after 2100 hours of service,
press the "Power Off" (not "Power On") button on the remote control for ten
seconds

Replace the bulb.

Hi,

Ballast is nothing but it is lamp power unit so here high voltage operating unit. While change the unit please check the voltage ratting and model. connector model and then replace.

Regards,
prakash

If it is a lamp error try this:
When the lamp exceeds 2100 hoursof service, the projector cannot turn on and the manu is not displayed. Do the following:
For VT670/VT470 Press the help button on the remote control for a minimum of ten seconds.
For VT570/VT47 Press and hold the power and the exit buttons on the remote control simultaneously for a minimum of ten seconds. When the lamp time clock is reset to zero, the lamp indicator goes out. Hope this helps! :]

Try pressing the HELP button. Don't release and press the power button. The LED lights should blink. Release then try to power on again.

If it is a lamp error try this:
When the lamp exceeds 2100 hoursof service, the projector cannot turn on and the manu is not displayed. Do the following:
For VT670/VT470 Press the help button on the remote control for a minimum of ten seconds.
For VT570/VT47 Press and hold the power and the exit buttons on the remote control simultaneously for a minimum of ten seconds. When the lamp time clock is reset to zero, the lamp indicator goes out. Hope this helps! :]

I had the same questions and decided to push power on and hold the help button as soon as soon as the power light came on. 10 secs later and the light was working again! Try grabbing a different NEC projector's remote, maybe it will have a help button.