How to repair Mactintosh HDD
If your goal is to install macOS Sierra, then your best bet is to boot into macOS Recovery using the ShiftOption⌘R keyboard shortcut. That's because your model MBP originally shipped with macOS Sierra and this keyboard shortcut is designed to install the version of macOS that originally shipped with your Mac.* 

To do this:


Fully shut down your MBP
Power up your MBP again but immediately press and hold the ShiftOption⌘R
Keep the keys down until you see either an Apple logo or spinning globe appear on screen (Note: If you have a firmware password set on your system, then let go of the keys when the password prompt appears)
Once the Utilities window appears you'll be in macOS Recovery Mode


Now choose to reinstall macOS and follow the prompts.

IMPORTANT - If you already have data stored on your internal drive you should do a backup first!

* For users of older Mac models this option will install the closest version of macOS still available to the original that shipped with it.