Power on and ready not reached by the copier

default must be no password , here are the steps to reset the printer
NVRAM reset for the HP LaserJet 400 colorMFP M475dn (Confirmed functional) 1: Print configuration page before beginning reset
2: Disconnect all cables except for power
3: While printer is in ready state, note the position of "Ready" message on the screen (Probably bottom right)
4: Power off the printer via power button
5: Touch the location on the screen where "Ready" message appeared.
6: while touching the screen, power on the printer. Continue to hold the screen.
7: When "Memory Limit Reached" message appears, release the screen.
8: Printer will reboot, clean and calibrate
9: Return cables to their appropriate ports
10: Print configuration page to confirm settings are cleared. Restore settings desired manually.
Finally have access back!

try reinstall software

49.4CF1 = gen firmware error-
Common problem on LJ9000 series. most likely a corrupt file has been sent to print,
How to Clear- switch printer OFF
if the net card is not built into the formatter- then unscrew and remove - remove all network/USB points from printer and then cycle the power- leave the printer disconnected from network and allow to reach ready state( If the machine still shows error- read below) if the machine does clear and reach ready then the error is with a bad file in the Print Spooler Que and may still need to be cleared from the print que (on the PC). If the error does not clear then you may need to Reset the machine - to perform a cold reset.
Switch power ON- Wait until Memory Check is Running( lots of asterisks on screen) whilst the mem check is running press and HOLD the green Tick button, Hold until all Three Heartbeat lights have come on together- let go of the tick button use the scroll buttons to navigate down to Cold Reset select and press tick cold reset is now performed- if this doesnt clear your issue then please contact your service Department and inform them that a new formatter may well be required-this repair can be completed using Belmonte Business Equipment.co.uk

It can be motor error or cartridge issue..

Recommended action:
1. Turn off the power by using the power switch, and then wait at least 30 seconds.
2. Turn on the power and wait for the product to initialize.

If the error persists, replace the developer motor.
If the error persists, replace the DC controller.

**If you need any technical help on printer then you can reach at http://www.vtechsquad.com/

Which printer model you are using??
Example: For cannon printer follow the given steps....

• Plug in power cable

• With the printer power turned off,while pressing RESUME/CANCEL button,press and hold the POWER ON button. (Do not release the buttons)

• When the Power LED lights in green,while holding the POWER ON button,release RESUME/CANCEL button. (Do not release the POWER ON button)

• Press RESUME/CANCEL buttons 5 times. (Each time the RESUME/CANCEL button is pressed,the ALARM and POWER LED lights alternately. Alarm in orange and power in green).

• When the POWER LED lights in green the printer is in service mode and ready for service operations.

***If you need any technical help on printer then you can reach at here

Do you have any flashing codes on the machine? I have seen empty toner cartridges with flakey chips on them cause that problem. Seems they run out of ink and the chip doesnt know what message to send and they just never come to ready.

this problem is usually caused by an eio card in the printer, ( jet direct card or hard disk), first thing to do is to remove these cards and reboot with only the power cable connected to the printer, once this reboots if the printer reaches a ready state print a test page directly from the printer, if this prints fine, then the actual printer hardware is fine, then it is a matter of rebooting with the jet direct installed, if the printer hangs problem with the card needs replaced, if this works fine, them do the same thing with the hard disk,

With the power off press and hold the cartridge cleaning button and the paper feed button. While holding the 2 buttons turn the power on. When the light for paper feed begins to flash let go of the buttons and immediately press and hold the cartridge cleaning button for at least 10 seconds. The unit will cycle then go to ready. The problem is that the counter for the waste ink cleaning pad has reached the limit.

I am not 100 percent sure what is happening to your machine after it comes to ready, but I will offer some thoghts.
If it comes to ready and then goes back to a low heat situation. It very well could be the board if it doesnt maintain heat.
Now that being said, once a coiper comes to ready and reaches full heat, it will switch over to pulsating the heat roller, not staying on fully all the time. That is how fusers are designed. Full on until they reach operating temperature, then pulsating to maintain the rollers heat level.
If you are having a problem with the image not fusing to the paper, you may have an issue with the pressure roller not making good contact with the heat roller.
There may be a software setting that needs adjusted to increase the fuser operating temperature.
The flickering heat rod, once the machine reaches ready, seems appropriate.
If you want more of an idea, can you be more specific as to whether the machine is faulting out with an under heating situation, or is the image not fusing to the paper properly?

had the same problem: took the tray away and found a sheet of paper in the printer not alawing
the tray sensor to work properly!!! after that the prob was solved.