That is the start menu. the command is meant to re register the start menu as well as everything listed in it.
did sfc /scannow find anything it couldn't fix?
Win 10 could have been corrupted by the power cut as its not designed to lose total power , by default its off state is actually a hybrid hibernate so it is possible you broke part of it with the power loss. I have seen it before. Simply unplugging it and opening case/cleaning inside has caused problems before.
A clean reinstall of it might be what you need. No rush. and its your choice when, or even if, I just think it is fastest way to fix. Good thing about knowing is you can plan what you need to save, and can make sure you don't lose anything if you list down things you need to save. If you have 2 or more drives in PC you can copy anything onto another drive and lose nothing but time.
On another PC, download the
Windows 10 media creation tool and use it to make a win 10 installer on USB
when you sure you have everything off C you want to keep
boot from installer and follow this guide:
https://forums.tomshardware.com/faq/how-to-do-a-clean-installation-of-windows-10.3170366/
Clean install wipes entire drive C is on, so no point putting things in another partition on same drive.