I cannot boot up Win10

NavyLCDR said:

What I would do, if you have space on the hard drive:

You'll need two USB flash drives or blank DVDs. One will be Windows 10 install media created either from Media Creation Tool or ISO from Microsoft Tech Bench. The other will be Kyhi's recovery drive. Boot the computer from Kyhi's recovery drive flash drive or DVD. Use MiniTool Partition Wizard to shrink the Windows partition by 50GB, making the free space at the end of the partition is easier/quicker than from the front. Don't forget to click the apply button!

When you have 50GB free space on the hard drive, boot the computer from the Windows 10 installation flash drive or DVD. Select the custom install option. Install Windows 10 to the 50GB free space you created.

See how the computer acts on the fresh install of Windows 10 - this will not affect your old Windows 10. In fact, it should set up dual booting. Then we will go from there.

Kyhi's recovery drive:
Windows 10 Recovery Tools - Bootable Rescue Disk - Windows 10 Forums

Windows 10 Media Creation Tool:
Windows 10

Microsoft Tech Bench:
Tech Bench

Hello NavyLCDR:
Thanks for your suggestions. I'm gonna try it shortly. Saying the other way: Win10 is my very first system which causes so many serious problems. My adventure with Windows started from Win3.1 and I went through all of them with exception of Win8 (and 8.1) including WinNT and Win2000. I had no major problems with any of them. Just this Win10. So I don't know what to think about it.

dencal said:

What is this, a bloody inquisition, I offered a suggestion going on what I interpreted from his post, as explained in my previous post.

Hello dencal:
No reason to get mad. Navy is right. I can't go after your suggestion because I simply can't get booted. Power goes off at some moment while booting. Sometimes sooner, sometimes later. But always before welcome screen shows up.
But thanks anyway for your try.

Oooops. It looks like we have problem. Power goes off while loading files from bootable Kyhi's DVD. IS this hardware problem? Computer is powered via power supply. Battery indicator shows battery 100% full. What can be wrong? And how to test it?

jadom said:

Oooops. It looks like we have problem. Power goes off while loading files from bootable Kyhi's DVD. IS this hardware problem? Computer is powered via power supply. Battery indicator shows battery 100% full. What can be wrong? And how to test it?

OK. I've pulled battery out and tried to boot up my laptop. Guess what? It started flawlessly. So it looks like battery failure was causing a problem. I have to examine this thing a few more times to mark this issue as solved. I'll do it later. Thanks to all of you for your help. And, I hope, it was it. If not - you will hear from me again shortly.

After several starts - NO PROBLEM. Everything seems to be OK. I think that battery failure caused my problem. I have to replace it. I also have to correct my opinion about Win10: it would be great if MS team as well as computer components manufacturers remember about people using older stuff and make new system supporting components, let's say, up to 10 years old. Well....this is my (and not only my) dream. It would let to avoid many BSOD's or crashes...

I am marking this thread as "solved". Thanks again to all participants for their involvement.