Hi, I am Dave, I will help you with this.
The power outage may have corrupted the Windows boot partition.
Disconnect any external drives or disks that may be connected to your PC.
Boot your system into BIOS, find the option to restore BIOS defaults and apply that
Then go to the Boot Priority list and ensure the internal drive or 'Windows Boot Manager' is set as the primary boot device.
Save those settings and restart your PC to see if Windows boots up correctly.