Cannot boot up after Windows 10 install.

[Dianne_3]

I press the power button and the wondows thngy begins to spin an immediately says "Shutting down".

 

[Colif]

Do you have a win 10 installer?

Get it here

change bios boot order so USB or DVD first, HDD second
boot from installer
on screen after language choices,, choose repair this PC, not install
choose troubleshoot
choose advanced
choose start up repair - this will scan pc and may fix problem - will ask for logon info

if that doesn't work, try this:
boot from installer again, choose repair this PC again
choose troubleshoot
choose advanced
choose start up options
should be 3 safe modes available, choose one of them (doesn't matter which)
PC will restart in safe mode, you don't have to do anything here, sometimes just going into safe mode is enough, restart PC and see if its fixed.

Hope that helps