Hello and welcome to JustAnswer, I look forward to assisting you today. Is there anything on the screen when you try to boot?
What is the make and model of the computer please?
Please disregard the popup for the Premium Service. That is automated and not coming from me.
Home built I take it? Do you see even a blinking cursor on the monitor when you boot?
This might sound silly, but do you have another monitor you can connect to rule that out?
I understand. Even if you had a major failure of the computer, you should still see the POST screen or at the very least a blinking cursor. Do you have dual monitors connected?
Then I would start with the peripherals inside the computer. Any one of the boards connected to the motherboard can be causing this problem. The only way to resolve it is through the process of elimination. Start by removing one of the video cards then restart the computer. If no difference, swap the cards and try again. Do the same with the RAM and any other card you might have installed.
You might even have a bad power supply. Try unplugging it for 30 minutes or so and then try starting it up to see what happens.
How about the RAM?
Okay. Well I can't tell you for sure what is causing this. I have experienced this myself and the last thing I tried was the power supply which corrected the problem.
Okay. I think we have tried everything there is to try except swapping the monitor and the power supply. Did you leave it unplugged then try starting it up?
Okay, do that. Leave it unplugged for awhile then try it again. How old is the computer?
Okay. Try unplugging it for awhile then and let me know what happens.
I thought you hadn't tried that yet?
You could. I want to make sure it is cooled down well enough before you restart.
If that doesn't work, you don't have many options left.
Look closely at the motherboard at the tops of the capacitors. They should all be flat on top.
Have you checked the board yet?
You checked all the capacitors?
Okay. Well just leave it unplugged for awhile then see what happens and let me know.
Let me know the results.
Just thought I would check to see how you came out. Let me know if I can be of further assistance.
The only thing left that I can think of then is the motherboard. There may be a jumper on the board to clear the CMOS. If not, pull the battery and let it set for several minutes to see if that will clear it. If that doesn't work, I am out of ideas. Let me know.