Adding short delay and LED indicator to show that the app is running

main.py

@@ -259,7 +259,7 @@ def register_ha_discovery(mqtt):
 
 
 # -------------------------------------------------------------
-# Main Execution Loop
+# Instantiate Wi-Fi connection
 # -------------------------------------------------------------
 def connect_wifi():
     wlan = network.WLAN(network.STA_IF)
@@ -277,6 +277,21 @@ def connect_wifi():
     print(f"Wi-Fi connected. IP: {wlan.ifconfig()[0]}")
 
 
+# -------------------------------------------------------------
+# Panic when the sensor isn't ready
+# -------------------------------------------------------------
+def panic(err=None):
+    """Signals a fatal fault by blinking the onboard LED continuously."""
+    if err:
+        print(f"Fatal error: {err}")
+    led = Pin("LED", Pin.OUT)
+    while True:
+        led.toggle()
+        time.sleep(0.1)
+
+# -------------------------------------------------------------
+# Main Execution Loop
+# -------------------------------------------------------------
 def main():
     # Adjust SDA/SCL pins according to your wiring
     i2c = SoftI2C(sda=Pin(16), scl=Pin(17), freq=100000)
@@ -322,4 +337,13 @@ def main():
 
 
 if __name__ == "__main__":
-    main()
+    # Allow 3.3V power rails and I2C registers to settle on cold boot
+    time.sleep(2)
+    
+    # Indicate startup has begun
+    Pin("LED", Pin.OUT).on()
+
+    try:
+        main()
+    except Exception as e:
+        panic(e)