Hp media centre m1180n wont power up after power cut

I believe your power supply has gone out.

Some of them have onboard fuses but I find that it is usually the board itself that goes out.

They vary in price but you may need the MFR power supply in order to fit your case.

Ebay is a good source.

If you haven't already done so, have a look at 'Troubleshooting Power Supply Issues' here
http://h10025.www1.hp.com/ewfrf/wc/document?docname=bph06788&tmp_task=solveCategory&cc=us&dlc=en&jumpid=reg_r1002_usen_c-001_title_r0001&lc=en&product=443756
(found by searching hp website for 'm1270n' > Support & Troubleshooting for your HP media centre m1270n Desktop PC > Solve a Problem > Start-up/Shutdown/Power > Power Management - Trouble Shooting Issues > (there's a section titled 'Power Supply Light is On or Flashes)

12.April.2014

I've had this happen and was able to resolve by removing the power cord for about a minute.
If still nothing, remove the side panel and inspect the motherboard for melting or charring. If you see some you will need to replace the motherboard, if none is present, start by replacing the power supply. Still nothing then it's motherboard replacement
There is a possibility the spark fried more than just the motherboard.

Comment back if you need clarification or more help.

Actually it boots, just that you don't see it. Try using another monitor - even a tv will do: disconnect the present monitor, connect the new one and reboot. If you get an image then the monitor is dead, replace it. If you don't then the onboard video card id dead, get a new one and try again. If even now it.s dead then you need a new motherboard.

This sounds like either your motherboard or power supply is shot, if it is still under warranty you can get HP to send you a new power supply or send your PC back to them and they should fix it for you.
You can check your warranty status online on HP's website here.
Hope this helps.

power unit PSU dead is there a fan motion ? beware of PSU that sleep in the night ... mine did it and destroyed the syste, also the auto safety may have dumped out and it will not resume unless the system is repaired, could be power or maybe an internal chip Memory short, processor dead, fan stopped inside ... never run without it there may be a loose connection stopped fan . Mike

yes u can, test it with another PSU...good luck.

why wont you buy a new power supply or a plug that converts from a 20 pin to a 24 pin

if your network cable is plugged in it will flash green .....if it won't turn on pull the plug and wait 10 seconds or more then plug in again and see if it will start .....are the fans running and no signal to monitor?

your power supply is possibly dead unplug it and smell the vents if you get a strange smell it has poped a capacitor or 2 try another psu from another pc loose before you buy a new one many a time a voltage spike may have done more damage depending where it got to