Computer switches an and off itself

I cannot figure this out.  When my PC is switched on, the green LED lights on both the DVD writer and the power switch come on, the case fans are heard to turn but, after just a few seconds, the power turns off and immediately thereafter the power comes back on and, once again the green LED lights comes on, the case fans turn but again, after just a few seconds, the power turns off and the whole process is repeated again and again.  The only way to then turn the PC off is to disconnect from the mains.  

The screen remains blank all the time, the PC does not boot at all even if the PC is left powering and switching off itself.  Is there an explanation for this strange process?  Can someone please help?

remove all power from the pc, and then reset the bios by either removing the motherboard battery and replacing it again or by using the cmos jumper if you know where it is.

after that reconnect the power and see if it will power on.

http://www.wikihow.com/Reset-Your-BIOS

Many thanks.  I did as suggested and now the computer is working fine.

you're welcome.

I cannot figure out what’s gone wrong.  Now when I switch on, the Windows 10 Logo appears and underneath the spinning dotted semicircle but after a while, the screen goes blank.  The PC does not boot at all.

Then after a few seconds, both the Windows Logo and the spinning dotted semicircle again appear but this tiime, a message on the screen says  “Preparing Automatic Repair”, and then “Diagnosing Your PC”.  Thereafter, another message appears on the screen saying “Your PC did not start correctly.  Press Restart to start your PC which can sometimes be the problem.  You can also press “Advanced Options to try other options to repair your PC”

I have pressed Restart and under “Advanced Options”, I have tried everything but to no avail.  The PC simply will not boot but the aforegoing process continues endlessly.  The only alternative then is to switch off the power.

It is unlikely that the problem is with the hard drive as it works fine on another PC.  I have also changed the battery but in vain.  What then could be the problem?

 

It is unlikely that the problem is with the hard drive as it works fine on another PC.

i assume by that you mean it boots to the os fine in the other pc.

if so then to me that sounds like you installed the os in the other pc and then put the drive in this one thinking it will boot up just fine.

it won't.

you need to do the os install on the pc the os will be running on because the hardware in each pc is different and that's why it won't boot up when put in a different pc.

if you only meant the drive and files can be seen on the other pc then that wouldn't rule out a hard drive problem which may have corrupted something stopping the os from booting either.

seeing how the inbuilt repair options don't seem to be able to fix the problem, i'd first try using a separate windows 10 repair disk and failing that i'd probably reinstall windows. once windows boots again i'd run some hard drive tests to see if it has any problems.