return if no ntp update possible

src/XD0OTA.cpp

@@ -18,11 +18,14 @@ void XD0OTA::setClock() {
 
   Serial.print(F("Waiting for NTP time sync: "));
   time_t now = time(nullptr);
+  int tries = 0;
   while (now < 8 * 3600 * 2) {
     yield();
     delay(500);
     Serial.print(F("."));
     now = time(nullptr);
+    tries++;
+    if (tries>15) return;
   }
 
   Serial.println(F(""));