I have a similar problem, after starting the MM the screen freezes, only way to unfreeze it is to close electron. Have tried both options too.
After enabling either of the OpenGL drivers i get the followed errors:
> magicmirror@2.4.0 start /home/pi/MagicMirror
> sh run-start.sh
libGL error: MESA-LOADER: failed to retrieve device information
MESA-LOADER: failed to retrieve device information
MESA-LOADER: failed to retrieve device information
Starting MagicMirror: v2.4.0
Loading config ...
Loading module helpers ...
No helper found for module: alert.
No helper found for module: MMM-Cursor.
Initializing new module helper ...
Module helper loaded: updatenotification
Initializing new module helper ...
Module helper loaded: MMM-Buttons
Initializing new module helper ...
Module helper loaded: MMM-DWD-WarnWeather
Initializing new module helper ...
Module helper loaded: MMM-DHT-Sensor
No helper found for module: clock.
No helper found for module: compliments.
No helper found for module: helloworld.
Initializing new module helper ...
Module helper loaded: MMM-Remote-Control
Initializing new module helper ...
Module helper loaded: MMM-MyWeather
No helper found for module: MMM-SimpleLogo.
Initializing new module helper ...
Module helper loaded: MMM-PiLights
All module helpers loaded.
Starting server on port 8080 ...
Server started ...
Connecting socket for: updatenotification
Connecting socket for: MMM-Buttons
Starting node helper for: MMM-Buttons
Connecting socket for: MMM-DWD-WarnWeather
MMM-DWD-WarnWeather helper started...
Connecting socket for: MMM-DHT-Sensor
MMM-DHT-Sensor helper started ...
Connecting socket for: MMM-Remote-Control
Starting node helper for: MMM-Remote-Control
Connecting socket for: MMM-MyWeather
MMM-WunderGround helper started ...
Connecting socket for: MMM-PiLights
[2018-07-03 15:42:24] [MMM-PiLights] Starting node_helper
Sockets connected & modules started ...
Launching application.
(node:1057) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): TypeError: Cannot read property 'refs' of undefined
(node:1057) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
(node:1057) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): TypeError: Cannot read property 'refs' of undefined
(node:1057) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 3): TypeError: Cannot read property 'refs' of undefined
(node:1057) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 4): TypeError: Cannot read property 'refs' of undefined
(node:1057) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 5): TypeError: Cannot read property 'refs' of undefined
(node:1057) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 6): TypeError: Cannot read property 'refs' of undefined
(node:1057) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 7): TypeError: Cannot read property 'refs' of undefined
Edit: MM works without any OpenGL Drivers, but CPU usage is pretty high and the Node errors are still there.