Chuwi Hi10 Plus Bootloader error

Obviously you did not follow the correct procedure and I understand that it will be difficult to choose the boot with Windows unless you can, with a bootable USB flash drive of Windows 10 and pressing F7 intermittently at boot, so that the boot selection screen appears. and in it, choose Windows.
In case it does not work, you must do a clean installation of Windows following the steps in this tutorial: