fixed.

src/main.cpp

@@ -77,8 +77,9 @@ void callback(char* topic, byte* payload, unsigned int length) {
   StaticJsonDocument<1024> jsonDoc;
   deserializeJson(jsonDoc,recBuf);
   const char* theText=jsonDoc["status"];
+  Serial.println(theText);
 
-  isOpen=strncmp(theText,"opened",6)!=0;
+  isOpen=(strncmp(theText,"opened",6)==0);
   Serial.println(isOpen?"CALLBACK: OPEN":"CALLBACK: CLOSED");
 }
 
@@ -88,6 +89,10 @@ void setup() {
 
   pinMode(LED_BUILTIN, OUTPUT);
   setup_wifi(); 
+  digitalWrite(LED_BUILTIN, HIGH);
+  delay(1000);
+  digitalWrite(LED_BUILTIN, LOW);
+  delay(1000);
   client.setServer(mqtt_server, 1883);
   client.setCallback(callback);
 }
@@ -98,11 +103,16 @@ void loop() {
   }
   client.loop();
   
+  // !!!! Funny enough - the meaning of the BuiltIn - LED is INVERTED, HIGH is off!!!
+  digitalWrite(LED_BUILTIN, HIGH);
+  delay(400);
+
   if (isOpen) {
-    digitalWrite(LED_BUILTIN, HIGH);
+    digitalWrite(LED_BUILTIN, LOW);
     delay(400);  
+    Serial.print("+");
+  } else {
+    Serial.print("-");
   } 
 
-  digitalWrite(LED_BUILTIN,LOW);
-  delay(400);
 }