Wheres Leap 42.3 installed and ran well on the Lenovo W530 laptop, Leap 15 Installation stalls early, in the first minute or so; the three-fold green bar simply freezes and nothing happens after that. Also, when I re-install Leap 42.3 and try to UPGRADE to Leap 15, the same freezing of the green bar is observed. On the other hand, installation of Leap 15 to two other Lenovo laptops (T530 and T430), using the same installation DVD, worked well. What else can I try?
At the initial screen with the highlight on Installation, hit the e key, navigate down to splash=silent quiet and remove them. Then you can proceed without the splash screen and watch the boot messages for errors to report here. Because you have Optimus, you may need at the same place to append nomodeset.
With a working 42.3 you can do an online upgrade to 15.0 with zypper instead of using installation media.