It finally worked for me, after reinstalling raspbian. Thanks you everyone for your help!

Thanks a lot to both of you. I will inform you about the results, as soon as I have it done.

I will certainly let you know. Do you think that it would be better to run the automatic installation command or manually install nodejs, clone the rep and the install npm?

No, only this, but I first followed wrong instructions and installed unnecessary software that might have somehow affected the other installations.

I had done just that, even before your post. And when i run nodejs -v it outputs v6… which is just fine. I don’t know, maybe I will reinstall raspbian and start it all over again

I get an error every time. Both with npm install electron and by reinstalling the whole package. I dont get what the error is but it seems to be with nodejs.

Ok it is now working.
I will now try to enable kioskmode.

I get a whole bunch of errors, but the output tells me that I either have wrong versions of nodejs or npm or the magicmirror package itself is the one to blame. After that comes the message that electron js/electron.js fails
Here is the log file that need to be submitted according to the log output:

0 info it worked if it ends with ok
1 verbose cli [ ‘/usr/bin/nodejs’, ‘/usr/bin/npm’, ‘start’ ]
2 info using npm@3.10.3
3 info using node@v6.5.0
4 verbose run-script [ ‘prestart’, ‘start’, ‘poststart’ ]
5 info lifecycle magicmirror@2.0.0~prestart: magicmirror@2.0.0
6 silly lifecycle magicmirror@2.0.0~prestart: no script for prestart, continuing
7 info lifecycle magicmirror@2.0.0~start: magicmirror@2.0.0
8 verbose lifecycle magicmirror@2.0.0~start: unsafe-perm in lifecycle true
9 verbose lifecycle magicmirror@2.0.0~start: PATH: /usr/lib/node_modules/npm/bin/node-gyp-bin:/home/pi/MagicMirror/node_modules/.bin:/usr/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/local/games:/usr/games
10 verbose lifecycle magicmirror@2.0.0~start: CWD: /home/pi/MagicMirror
11 silly lifecycle magicmirror@2.0.0~start: Args: [ ‘-c’, ‘electron js/electron.js’ ]
12 info lifecycle magicmirror@2.0.0~start: Failed to exec start script
13 verbose stack Error: magicmirror@2.0.0 start: electron js/electron.js
13 verbose stack spawn ENOENT
13 verbose stack at ChildProcess. (/usr/lib/node_modules/npm/lib/utils/spawn.js:33:16)
13 verbose stack at emitTwo (events.js:106:13)
13 verbose stack at ChildProcess.emit (events.js:191:7)
13 verbose stack at maybeClose (internal/child_process.js:877:16)
13 verbose stack at Process.ChildProcess._handle.onexit (internal/child_process.js:226:5)
14 verbose pkgid magicmirror@2.0.0
15 verbose cwd /home/pi/MagicMirror
16 error Linux 4.4.13-v7+
17 error argv “/usr/bin/nodejs” “/usr/bin/npm” “start”
18 error node v6.5.0
19 error npm v3.10.3
20 error file sh
21 error code ELIFECYCLE
22 error errno ENOENT
23 error syscall spawn
24 error magicmirror@2.0.0 start: electron js/electron.js
24 error spawn ENOENT
25 error Failed at the magicmirror@2.0.0 start script ‘electron js/electron.js’.
25 error Make sure you have the latest version of node.js and npm installed.
25 error If you do, this is most likely a problem with the magicmirror package,
25 error not with npm itself.
25 error Tell the author that this fails on your system:
25 error electron js/electron.js
25 error You can get information on how to open an issue for this project with:
25 error npm bugs magicmirror
25 error Or if that isn’t available, you can get their info via:
25 error npm owner ls magicmirror
25 error There is likely additional logging output above.
26 verbose exit [ 1, true ]

I get the “this site cant be reached” error

No, i am not. I am using the Raspberry Pi 3 Model B.