diff --git a/rtlplayground.c b/rtlplayground.c
index 358650d..2355854 100644
--- a/rtlplayground.c
+++ b/rtlplayground.c
@@ -30,6 +30,8 @@ extern __xdata uint32_t flash_size;
 extern __xdata uint16_t crc_value;
 __xdata struct machine_runtime machine_detected;
 void crc16(__xdata uint8_t *v) __naked;
+void flash_default_config(void);
+void early_boot_handle_button(void);
 
 // See setup_serial_timer1() for valid baudrate settings!
 #define SERIAL_BAUD_RATE 115200
@@ -735,6 +737,64 @@ void delay(uint16_t t)
 		PCON |= 1;
 }
 
+void early_boot_handle_button(void)
+{
+	if (machine.reset_pin == GPIO_NA)
+		return;
+
+	gpio_input_setup(machine.reset_pin);
+
+	// Debounce after init
+	delay(100);
+	// If the button is not already held at boot, continue normally.
+	if (gpio_pin_test(machine.reset_pin))
+		return;
+
+	set_sys_led_state(SYS_LED_FAST);
+	print_string("\n[Reset button held at boot]\n");
+
+	if (gpio_pin_test(machine.reset_pin))
+		return;
+
+	const __xdata uint32_t min_hold_ticks = 10UL * SYS_TICK_HZ;
+	const __xdata uint32_t max_hold_ticks = 30UL * SYS_TICK_HZ;
+	const __xdata uint32_t blink_ticks = SYS_TICK_HZ / 10;      // 100 ms
+	const __xdata uint32_t pause_ticks = SYS_TICK_HZ / 2;       // 500 ms
+	__xdata uint32_t start_ticks = ticks;
+	__xdata uint32_t last_blink_step = start_ticks;
+	__xdata uint8_t blink_step = 0;
+
+	set_sys_led_state(SYS_LED_ON);
+
+	while (!gpio_pin_test(machine.reset_pin)) {
+		__xdata uint32_t held_ticks = ticks - start_ticks;
+
+		if (held_ticks > max_hold_ticks) {
+			print_string("[Button held >30s at boot; continuing normal boot]\n");
+			return;
+		}
+
+		// Double blink pattern while button is held:
+		// ON (100ms), OFF (100ms), ON (100ms), OFF (500ms)
+		__xdata uint32_t step_ticks = (blink_step == 3) ? pause_ticks : blink_ticks;
+		if ((ticks - last_blink_step) >= step_ticks) {
+			blink_step = (blink_step + 1) & 0x3;
+			set_sys_led_state((blink_step == 0 || blink_step == 2) ? SYS_LED_ON : SYS_LED_OFF);
+			last_blink_step = ticks;
+		}
+
+		PCON |= 1;
+	}
+
+	set_sys_led_state(SYS_LED_ON);
+
+	if ((ticks - start_ticks) >= min_hold_ticks) {
+		print_string("[Button held 10s-30s at boot; restoring default config]\n");
+		set_sys_led_state(SYS_LED_FAST);
+		flash_default_config();
+		delay(3UL * SYS_TICK_HZ);
+	}
+}
 
 /*
  * Configure the SerDes of the SoC for a particular mode
@@ -2134,6 +2194,8 @@ void main(void)
 //	p031f.a610:2058 p041f.a610:2058  p051f.a610:2058  r4f3c:00000000 p061f.a610:2058 p071f.a610:2058 
 	port_stats_print();
 
+	early_boot_handle_button();
+
 	execute_config();
 	print_string("\n> ");
 	idle_ready = 1;