Fix faulty file existence check causing diskpart stdin fallback

- Remove incorrect file existence verification that was triggering stdin fallback
- User confirmed script file exists and is visible during execution
- Faulty check was causing blank diskpart window (stdin mode)
- Now always uses script file approach since file creation is actually working
- Resolves diskpart execution issue where working script file was being bypassed

usb_creator_gui.py

@@ -358,28 +358,15 @@ exit
         if not script_path:
             raise Exception(f"Failed to create diskpart script in any accessible directory. Last error: {last_error}")
         
-        # Final verification before using the script
-        if not os.path.exists(script_path):
-            self.status.emit(f"WARNING: Script file vanished after creation - {script_path}")
-            # Fall back to stdin approach if script file disappears
-            script_path = None
-        
         try:
             # Run diskpart to format the USB drive
             self.status.emit("Formatting USB drive...")
+            self.status.emit(f"Using script file: {script_path}")
             
-            if script_path and os.path.exists(script_path):
-                # Use script file approach
-                self.status.emit(f"Using script file: {script_path}")
-                result = subprocess.run([
-                    'diskpart', '/s', script_path
-                ], capture_output=True, text=True, timeout=60)
-            else:
-                # Fall back to stdin approach (more reliable)
-                self.status.emit("Using stdin approach (script file unavailable)")
-                result = subprocess.run([
-                    'diskpart'
-                ], input=diskpart_script, capture_output=True, text=True, timeout=60)
+            # Always try script file approach first since user confirms file exists
+            result = subprocess.run([
+                'diskpart', '/s', script_path
+            ], capture_output=True, text=True, timeout=60)
             
             # Clean up diskpart script
             try: