Q: How to disable SIP booting in single user mode?

From the developers page: Security configuration is stored in NVRAM rather than in the file system itself. As a result, this configuration applies to all installations of OS X across the entire machine and persists across OS X installations that support System Integrity Protection.

To enable or disable System Integrity Protection, you must boot to Recovery OS and run the csrutil(1) command from the Terminal.

System Integrity Protection https://support.apple.com/en-us/HT204899

This command can be run without root privileges and will tell you if SIP is on or off.

to learn if SIP is enabled or disabled, run

csrutil status

to disable SIP:

copy & paste the following and then press Return:

csrutil disable

To enable SIP

csrutil enable

After enabling or disabling System Integrity Protection on a machine, a reboot is required.

There are options outlined here:

NetBoot, NetInstall, and NetRestore requirements in OS X El Capitan - Apple Support

If the graphics card has died, it probably is still under warranty: https://www.apple.com/support/macbookpro-videoissues/