don't touch that code if you don't even know about "Serial2"

src/modules/SerialModule.h

@@ -8,6 +8,8 @@
 #include "Router.h"
 #include <functional>
 
+#if (defined(ARCH_ESP32) || defined(ARCH_NRF52)) && !defined(TTGO_T_ECHO) && !defined(CONFIG_IDF_TARGET_ESP32S2)
+
 class SerialModule : public StreamAPI, private concurrency::OSThread
 {
     bool firstTime = 1;
@@ -68,3 +70,5 @@ class SerialModuleRadio : public MeshModule
 };
 
 extern SerialModuleRadio *serialModuleRadio;
+
+#endif