blinking external led with psu

technically works, but blinking incorrectly

sketch_aug25b_rgbblink/sketch_aug25b_rgbblink.ino

@@ -0,0 +1,43 @@
+#include <FastLED.h>
+
+#define LED_PIN     15
+#define NUM_LEDS    5
+
+CRGB leds[NUM_LEDS];
+
+void setup() {
+  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
+  FastLED.setBrightness(128);
+  FastLED.clear(true);
+}
+
+// Helper: blink one LED with a color then turn it off
+void blinkLED(int idx, CRGB color, int onMs = 300, int offMs = 150) {
+  if (idx < 0 || idx >= NUM_LEDS) return;
+  
+  leds[idx] = color;
+  FastLED.show();
+  delay(onMs);
+
+  leds[idx] = CRGB::Black;
+  FastLED.show();
+  delay(offMs);
+}
+
+void loop() {
+  // Make sure all LEDs start off
+  FastLED.clear();
+  FastLED.show();
+
+  for (int i = 0; i < NUM_LEDS; i++) {
+    // R -> G -> B for this LED
+    blinkLED(i, CRGB::Red);
+    blinkLED(i, CRGB::Green);
+    blinkLED(i, CRGB::Blue);
+
+    // Ensure it's off before moving on
+    leds[i] = CRGB::Black;
+    FastLED.show();
+    delay(200);
+  }
+}

sketch_may4b_nerdtutorialscp/sketch_may4b_nerdtutorialscp.ino

@@ -0,0 +1,20 @@
+#include <FastLED.h>
+
+#define LED_PIN     15
+#define NUM_LEDS    5
+
+CRGB leds[NUM_LEDS];
+
+void setup() {
+
+  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
+  
+}
+
+void loop() {
+  
+  leds[0] = CRGB(255, 0, 0);
+  FastLED.show();
+  delay(500);  
+  leds[1] = CRGB(0, 255, 0);
+}