Can't boot (prohibitory error).

[cmn699]

Since you are using the Integrated Graphics which I think is Skylake Intel HD 530, I hope you have already taken steps to edit the config.plist to avoid Graphics Glitch you will be facing on install.

From your description it looks like the USB port to which your installer is inserted is becoming non-functional and the system is unable to access data. Keeping the system with just the target HDD for macOS sierra installation , and removing all but the Sierra Installer USB , the Keyboard and Mouse in USB 2 ports and disconnecting all other USB devices may be the first step. Moving the USB installer to a back USB port is another step you can try.

Use verbose mode (-v ) to boot the Installer in addition to other needed boot flags. Take photos and upload the image file to the Forum for better help.

 

[cmn699]

In my above response I have made the usual assumption that the USB installer is created in an Apple or hackintosh using a guide like Unibeast with all the Do's and Don't s and therefore is not lacking any files needed for booting and installation.