diff --git a/src/gui/main_window.py b/src/gui/main_window.py
index eb37dfa..f40a61d 100644
--- a/src/gui/main_window.py
+++ b/src/gui/main_window.py
@@ -1823,7 +1823,7 @@ class MainWindow(ctk.CTk):
 
             # Abort if SD boot timeout fired
             if not self._is_running:
-                self._log_message(f"  ⚠ Step {i+1} aborted (SD boot mode)")
+                self._log_message(f"  ⚠ Step {i+1} aborted (SD boot mode — switch to QSPI)")
                 self._set_step_status(i, "error")
                 results.append(False)
                 break
@@ -2163,9 +2163,11 @@ class MainWindow(ctk.CTk):
     # ── SD Boot Detection ──────────────────────────────────────
 
     def _check_sd_boot(self, line: str) -> None:
-        """Scan a log line for SD boot mode; start 30s timer if detected."""
-        if self._sd_detected:
-            return
+        """Scan a log line for SD boot mode; start 30s timer if detected.
+        
+        New log output after detection resets the timer — recovery
+        may indicate the DIP switch was changed.
+        """
         import re
         for pattern in [
             re.compile(r"[Bb]oot\s*[Mm]ode\s*(?:is)?\s*[:\[=\s]*(\w+)"),
@@ -2173,10 +2175,18 @@ class MainWindow(ctk.CTk):
         ]:
             m = pattern.search(line)
             if m and m.group(1).upper() == "SD":
-                self._sd_detected = True
-                self._log_message("  ⚠ SD boot mode detected — waiting 30s for JTAG switch...")
+                if not self._sd_detected:
+                    self._sd_detected = True
+                    self._log_message("  ⚠ SD boot mode detected — waiting 30s for QSPI switch...")
+                else:
+                    self._log_message("  ⚠ SD boot mode still present — resetting 30s timer")
+                    self.after_cancel(self._sd_timer_id)
                 self._sd_timer_id = self.after(30000, self._on_sd_timeout)
                 return
+        # Any other log output resets the timer (boot mode may have changed)
+        if self._sd_detected:
+            self._log_message("  ✓ New output received — cancelling SD timer")
+            self._cancel_sd_timer()
 
     def _cancel_sd_timer(self) -> None:
         """Cancel the SD boot timeout if still pending."""
@@ -2189,12 +2199,12 @@ class MainWindow(ctk.CTk):
         """SD boot mode persisted 30s — kill hw_server, alert user, stop workflow."""
         self._sd_timer_id = None
         self._sd_detected = False
-        self._log_message("  ✗ SD boot mode persisted >30s — switch DIP to JTAG mode!")
+        self._log_message("  ✗ SD boot mode persisted >30s — switch DIP to QSPI mode!")
         self._kill_hw_server()
         from tkinter import messagebox
         messagebox.showerror(
             "启动拨码开关位置错误！",
-            "检测到 Boot mode 为 SD，请将拨码开关切换到 JTAG 模式后重试。",
+            "检测到 Boot mode 为 SD，请将拨码开关切换到 QSPI 模式后重试。",
         )
         # Stop current workflow execution
         self._is_running = False