What to do turned off the laptop during the update, it does not turn on. What to do?

Question

Iron

A friend brought a laptop, turned off when updating windows 8, does not turn on, writes “There was a problem on your PC and it needs to be restarted. We're just collecting some information about the error," then immediately reboot and go around.
I tried:
1) Make a system restore from the disk, copy the files, then the same error pops up as when you turn it on, only in English and reboots.
2) Install windows 7, copy files, a background appears on which the install button appears and immediately a blue screen appears with the error code "Stop: 0x00000034 (0x00000107, 0xc0000420, 0x00000000, 0x00000000)".
3) Go into safe mode (F8), does not enter, maybe another keyboard shortcut?
The hard disk is divided into 2 parts, into 2 there is a lot of important information, so that it is not desirable to format it, but it is possible at the very least.

Answer 1

SFC /scannow
or

DISM.exe /Online /Cleanup-image /ScanHealth
DISM.exe /Online /Cleanup-image /RestoreHealth

or
msdn.microsoft.com/en-us/library/hh825265.aspx
or rather/RevertPendingActions

Answer 2

The Stop error code says that the disk from which the installation is being performed may be corrupted. Try another or from a flash drive.

Answer 3

Well, since you have already started installing another windows, then:
- Make a backup copy of data
- Restore Windows 8 from a disk to a laptop or Recovery partition or ...
- Disable Secure boot in BIOS, set UEFI to legacy mode and install the newly purchased Windows 7 from DVD