El Capitan fiasco on macBook Pro late 2011

[Vladislav]

My brothers Macbook Pro late 2011 got an error while he was upgrading to El Capitan. And he cant do anything at this point, here is a screenshot that he got:

Any advice for him how to get his laptop back to work?

 

[Kissmyne]

Plug in the MBP, run Apple Hardware Tests.. explained here... https://support.apple.com/en-us/HT201257

If the hardware tests all pass, I recommend an Erase and Reinstall for the most astute resolution of this issue. This process is explained here.. https://support.apple.com/en-us/HT204904

Please keep in mind that an Erase and Reinstall will remove ALL data previously stored on the Mac, IF you have any files you need please backup first. Since this mac doesn't boot your best bet is Target Disk Mode.. explained here... https://support.apple.com/en-us/HT201462