Thanks for posting your question on Justanswer.com, a global paid independent support site.My Name is ***** ***** I will be assisting you today. Do you mean the power light has turned off ?
Thanks for the update and sorry for the late reply, unfortunately, the problem you are describing is a hardware fault and not a simple case of switch on or off. As you said that many customers have faced this same problem, it means this is a known issue for this printer model. The scanner lamp can be defective or the power circuit of the lamp is defective. In both the cases, you have to replace the defective parts to solve the problem. Although you can try the steps below, if you have not tried them already.
To perform a hard reset, leave the printer on and unplug the power cable for 1 minute. While it is unplugged, hold down the power button on the printer for 10-15 seconds to release any built up power, then after the minute has passed, plug the printer back in.
Also, Do you have the printer connected directly to a wall outlet or is it in a surge protector or power bar or UPS? Even if you have been using a surge protector/power bar all this time and you feel it is not the cause, please connect it to a wall outlet just so we can eliminate the power source as the root cause.
HP will never tell the customer, how to solve a hardware related problem, because if they tell then, their service center franchises will face losses.