Bootice Manual Better | !free!

REM backup current MBR BootICE.exe /DEVICE=0 /BACKUP_MBR /FILE=C:\sector0_mbr_backup.bin

Use the "Activate" button to set which partition is the primary bootable one. If your PC isn't booting because the wrong partition is "Active," this is your one-click fix. 3. UEFI Boot Entry Editing bootice manual better

A better approach is to practice on a USB drive first. Insert a spare flash drive and use Bootice on it—mistakes won’t kill your PC. REM backup current MBR BootICE

Make multi OS bootable USB drive including windows os and linux bootice manual better

Choose "Current System BCD" or "Other BCD file" if you are editing an offline drive.