The Error hard disk failure is imminent is worst that SMART error. If this problem appears backup your data immediately and replace the hard disk drive. The error indicates that your disk drive will fail sooner or later.
With the “hard disk failure is imminent error. Please back up your hard disk drive and have it replace” error message you can still proceed to the Windows boot up but most of the time the Windows system is already damage.
The thing you can do if the Windows was damage is connect the hard disk drive to another working computer and copy all your important files. Then throw away that disk drive.