16.04 - Trying to get my NVIDIA optimus card working

I have a dell l502x laptop with the infamously screwed up hybrid graphics card system (NVIDIA GT540m and Integrated Intel GC)

I have a freshly installed ubuntustudio 16.4.01 LTS running dual boot with windows 10; After installing the proprietary, tested NVIDIA driver 361- recommended at the 'Additional Drivers' tab, a reboot gives a blank screen with the mouse stuck at the top right corner, and nothing works but a forced reboot via long-pressing the main power button.

I have tried all the different driver versions and all the different PPA repositories (xorg-edgers, graphics-drivers etc), the same issue persists.

The system however reboots successfully if the 'intel' card is selected by the command

    sudo prime-select intel

when the NVIDIA card is selected

    glxgears

gives the following error

    Error: couldn't get an RGB, Double-buffered visual

command

    lspci -k | grep -EA2 'VGA|3D'

gives

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
Subsystem: Dell 2nd Generation Core Processor Family Integrated Graphics Controller

Kernel driver in use: i915

01:00.0 VGA compatible controller: NVIDIA Corporation GF108M [GeForce GT 540M] (rev ff)
Kernel modules: nvidiafb, nouveau, nvidia_361

     dkms status

bbswitch, 0.8, 4.4.0-38-lowlatency, x86_64: installed
nvidia-361, 361.42, 4.4.0-38-lowlatency, x86_64: installed

    glxinfo | grep OpenGL

Error: couldn't find RGB GLX visual or fbconfig