panicmode

Make a call to the server (use retrofit or volley, for example). It must provide a JSON with at least this:

{
  "disabled": false,
  "minVersion": "0",
  "disabledUrl": "http://www.baseUrl.com/panic/serverOff",
  "minVersionUrl": "http://www.baseUrl.com/panic/needsUpdate"
}

On response, call (WARNING! Import your apps BuildConfig):

handleResponse(context, BuildConfig.VERSION_CODE, jsonObject)

It will check versions and, if needed, close your app completely and open the provided URL.