diff --git a/__pycache__/csv_preprocessor.cpython-312.pyc b/__pycache__/csv_preprocessor.cpython-312.pyc
index ee65eac..7d7e578 100644
Binary files a/__pycache__/csv_preprocessor.cpython-312.pyc and b/__pycache__/csv_preprocessor.cpython-312.pyc differ
diff --git a/device_server.py b/device_server.py
index d049ed2..09cbc25 100644
--- a/device_server.py
+++ b/device_server.py
@@ -10,6 +10,7 @@ Add addresses to REGISTER_COMMANDS to capture more register ranges.
 
 import os
 import re
+import signal
 import subprocess
 import threading
 
@@ -20,7 +21,7 @@ app = Flask(__name__)
 # ---------------------------------------------------------------------------
 # Video playback state (managed as a subprocess)
 # ---------------------------------------------------------------------------
-KIOSK_SCRIPT = "/root/python/display_test_nexio.py"
+KIOSK_SCRIPT = "/root/display_test_nexio.py"
 
 _video_proc: subprocess.Popen | None = None
 _video_lock = threading.Lock()
@@ -88,14 +89,19 @@ def _parse_memtool_output(raw: str) -> list:
 
 @app.route("/display", methods=["PUT"])
 def control_display():
-    data  = request.get_json()
+    data  = request.get_json(force=True) or {}
     state = data.get("state", "").lower()
-    if state == "off":
-        os.system("echo 4 > /sys/class/graphics/fb0/blank")
-        return jsonify({"status": "Display OFF"}), 200
-    elif state == "on":
+    if state == "on":
+        with _video_lock:
+            if _video_proc is not None and _video_proc.poll() is None:
+                _video_proc.send_signal(signal.SIGUSR1)
+                return jsonify({"status": "video switched"}), 200
+        # fallback when video is not running
         os.system("echo 0 > /sys/class/graphics/fb0/blank")
         return jsonify({"status": "Display ON"}), 200
+    elif state == "off":
+        # nothing to do while video is managing the display
+        return jsonify({"status": "ok"}), 200
     else:
         return jsonify({"error": "Invalid state. Use 'on' or 'off'"}), 400
 
@@ -205,8 +211,8 @@ def control_video():
                 return jsonify({"status": "already_running", "pid": _video_proc.pid}), 200
             _video_proc = subprocess.Popen(
                 ["python3", KIOSK_SCRIPT],
-                stdout=subprocess.DEVNULL,
-                stderr=subprocess.DEVNULL,
+                stdout=open("/tmp/kiosk.log", "w"),
+                stderr=subprocess.STDOUT,
             )
             return jsonify({"status": "started", "pid": _video_proc.pid}), 200
 
diff --git a/display_test_nexio.py b/display_test_nexio.py
index 618efcb..54b5ae0 100644
--- a/display_test_nexio.py
+++ b/display_test_nexio.py
@@ -1,4 +1,5 @@
 import gi
+import signal
 import struct
 import os
 
@@ -129,6 +130,9 @@ def play_kiosk():
     manager = KioskManager(pipeline)
     pipeline.set_property("uri", manager.videos[0])
 
+    # SIGUSR1 → switch video (used by device_server PUT /display {"state":"on"})
+    signal.signal(signal.SIGUSR1, lambda sig, frame: manager.switch_video())
+
     # --- INPUT MONITORING ---
     try:
         btn_fd = open("/dev/input/event1", "rb")