fix: x10 Express boot freeze and bluetooth lockup (#3349)

* Fix attempt for boot issue

* fix: reset BT usart context after de-init

radio/src/storage/storage_common.cpp

@@ -21,6 +21,7 @@
 
 #include "opentx.h"
 #include "timers_driver.h"
+#include "tasks/mixer_task.h"
 
 #if defined(USBJ_EX)
 #include "usb_joystick.h"
@@ -60,7 +61,10 @@ void preModelLoad()
   logsClose();
 #endif
 
-  pulsesStop();
+  if (mixerTaskStarted()) {
+    pulsesStop();
+  }
+
   stopTrainer();
 #if defined(COLORLCD)
   deleteCustomScreens();
@@ -182,7 +186,13 @@ void postModelLoad(bool alarms)
     PLAY_MODEL_NAME();
   }
 #endif
-  pulsesStart();
+
+  // Mixer should only be restarted
+  // if we are switching between models,
+  // not on first boot (started later on)
+  if (mixerTaskStarted()) {
+    pulsesStart();
+  }
 
 #if defined(SDCARD)
   referenceModelAudioFiles();