I had more or less the same problem in my laptop and in my main PC. But you can get around it just by login again and doing the update through zypper. I believe it restarts the session 3 times, and one of those after login, you just have a black screen. Use Ctrl+Alt+T to bring up the terminal and zypper dup again. After zypper is done just restart and everything will be fine.
Did this with both PCs and both are working with no problems.