diff --git a/frontend/src/simulation/RaspberryPi3Bridge.ts b/frontend/src/simulation/RaspberryPi3Bridge.ts
index dc1e9760..4428f2b1 100644
--- a/frontend/src/simulation/RaspberryPi3Bridge.ts
+++ b/frontend/src/simulation/RaspberryPi3Bridge.ts
@@ -105,7 +105,13 @@ export class RaspberryPi3Bridge {
   }
 
   connect(): void {
-    if (this.socket && this.socket.readyState !== WebSocket.CLOSED) return;
+    const state = this.socket?.readyState;
+    if (state === WebSocket.OPEN || state === WebSocket.CONNECTING) return;
+    // A socket in CLOSING is on its way out, not usable: the old guard
+    // treated it as live and returned, so "restart in Linux mode" right
+    // after a run silently did nothing — no boot, and the toolbar still
+    // showing Stop. Drop it and open a fresh one.
+    this.socket = null;
 
     const base = API_BASE();
     const wsProtocol = base.startsWith('https') ? 'wss:' : 'ws:';
diff --git a/frontend/src/store/useSimulatorStore.ts b/frontend/src/store/useSimulatorStore.ts
index a2cab443..0bf8cea4 100644
--- a/frontend/src/store/useSimulatorStore.ts
+++ b/frontend/src/store/useSimulatorStore.ts
@@ -1929,11 +1929,18 @@ export const useSimulatorStore = create<SimulatorState>((set, get) => {
         // booting a Linux guest (a backend process + ~90 s). The detector
         // lives in the overlay; `enginePinned` lets the user override it.
         const decision = decideEngine(boardId, board.enginePinned);
+        // `running` is set here (not only by the toolbar): the Linux-mode
+        // button restarts the board directly, and without this the flag
+        // kept whatever the previous run left, so the UI showed Stop for
+        // a board that was not running.
         set((s) => ({
           boards: s.boards.map((b) =>
-            b.id === boardId ? { ...b, engineMode: decision.engine } : b,
+            b.id === boardId
+              ? { ...b, engineMode: decision.engine, running: true }
+              : b,
           ),
           serialMonitorOpen: true,
+          ...(s.activeBoardId === boardId ? { running: true } : {}),
         }));
         if (decision.engine === 'instant') {
           const instant = getInstantEngine();