fixed start btn not working

static/app.js

@@ -865,6 +865,14 @@ allFeaturesTextAddBtn.map((value, index) => {
   }
 });
 
+var startButton = document.getElementById("start-btn");
+// start the display
+startButton.addEventListener("click", () => {
+    fetch("/start", {
+      method: "PUT",
+    }); 
+});
+
 var brightnessButton = document.getElementById("brightness-btn");
 // start the display
 brightnessButton.addEventListener("click", () => {