Here is a slimmed down config which i tested on my PC, which works as expected but does not work on my Pi.

var config = {
    port: 8080,

    language: "en",
    timeFormat: 24,
    units: "metric",

    modules: [
        {
            module: "alert",
        },
        {
            module: "clock",
            position: "top_left"
        }
    ]
};

The log output when running npm run start:

> magicmirror@2.13.0 start /home/pi/MagicMirror
> DISPLAY="${DISPLAY:=:0}" ./node_modules/.bin/electron js/electron.js

[2020-10-26 14:46:47.896] [LOG]    Starting MagicMirror: v2.13.0
[2020-10-26 14:46:47.929] [LOG]    Loading config ...
[2020-10-26 14:46:47.951] [LOG]    Loading module helpers ...
[2020-10-26 14:46:47.960] [LOG]    No helper found for module: alert.
[2020-10-26 14:46:47.964] [LOG]    No helper found for module: clock.
[2020-10-26 14:46:47.966] [LOG]    All module helpers loaded.
[2020-10-26 14:46:48.502] [LOG]    Starting server on port 8080 ...
[2020-10-26 14:46:48.556] [LOG]    Server started ...
[2020-10-26 14:46:48.559] [LOG]    Sockets connected & modules started ...

After the last log line above, the application just exists out and no browser is opened.

Interestingly, running in server only mode works and I can browse to the UI no problem. Is it possible it’s something odd with electron. The version used is electron@6.0.12

Some other pieces of relevant info:

Version:

Raspberry Pi 2 Model B Rev 1.1

OS:

Distributor ID:	Raspbian
Description:	Raspbian GNU/Linux 10 (buster)
Release:	10
Codename:	buster

Be great to get some help on this, been digging down various rabbit holes few days now. Thanks.