I have the same problem. I bought the new dell inspiron 15 7000 series 7559. It has skylake 6700HQ processor and dual graphic adapter intel HD530 and Nvidia GTX960M.
First, I tried to install ubuntu 15.10 without luck, until I found in the forums that you must add boot arguments in GRUB, which are :
This must be done while booting the installer, and in booting the installed system as well.
Then everything works OK, with the intel low performance graphics.
Then I installed the nvidia-352 driver by doing:
sudo apt-get install nvidia-352
This installs dependencies, and other utilities, like nvidia-settings.
After reboot, everything works perfectly with the Nvidia graphic card always ON. I was able to start some games from steam platform.
Then comes the big question :
How to get BOTH intel and nvidia ?
Supposedly, nvidia-prime was installed and I was supposed to be able to switch the graphic card from the Nvidia settings panel (nvidia-setting).
NO WAY ! After changing to the Intel card, I am stuck at the ubuntu logo upon reboot !!
I tried various ways of installing bumblebee found in the forums, but always get stuck at the boot screen ...
I took care of finding my pci address for both cards with lspci and updated the bumblebee xorg conf files.
This is very similar to what happened before using the boot parameters mentionned above.
Is there any possibility that the parameters are not used after installin bumblebee ?
What is the logic or program flow during the bumblebee boot ?
I want to troubleshoot my problem, but I don't know where to look.
Any help/hints greatly appreciated !