Had the same problem.
Installed and reinstalled several times, manually and with the automated script.

It looked to me it was a problem installing grunt and electron.
I had to install them with sudo.
Still did not work, but when I renamed the magicmirror folder and “reinstalled” magicmirror using curl command with sudo, it worked.
Some privileges problem maybe somewhere?

Try:
npm install -g grunt
after them again npm install -g electron

Btw. how did you install the mirror? By yourself or with the suggested curl command?

npm WARN grunt-yamllint@0.2.0 requires a peer of grunt@~0.4.0 but none was installed.

No idea what means …

and when I tried to start magic mirror got this :

magicmirror@2.0.0 start /home/pi/MagicMirror
electron js/electron.js

npm ERR! Linux 4.4.32-v7+
npm ERR! argv “/usr/bin/nodejs” “/usr/bin/npm” “start”
npm ERR! node v6.9.1
npm ERR! npm v3.10.8
npm ERR! code ELIFECYCLE
npm ERR! magicmirror@2.0.0 start: electron js/electron.js
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the magicmirror@2.0.0 start script ‘electron js/electron.js’.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the magicmirror package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! electron js/electron.js
npm ERR! You can get information on how to open an issue for this project with:
npm ERR! npm bugs magicmirror
npm ERR! Or if that isn’t available, you can get their info via:
npm ERR! npm owner ls magicmirror
npm ERR! There is likely additional logging output above.

npm ERR! Please include the following file with any support request:
npm ERR! /home/pi/MagicMirror/npm-debug.log

Thanks for your suggestions - got any more idea’s ? as I’d really like to this working

I’ve googled it there seems a few people with the problem but no answers
Any help would be appreciated.