Merge pull request #2 from weebl2000/pr-1570-fix-heltec-v4-power

Fix double claim, eliminate dead code at compile time

src/helpers/ui/SSD1306Display.cpp

@@ -19,11 +19,9 @@ bool SSD1306Display::begin() {
 
 void SSD1306Display::turnOn() {
   if (!_isOn) {
-    if (_peripher_power) {
-        _peripher_power->claim();
-        begin();
-    }
-    _isOn = true;
+    if (_peripher_power) _peripher_power->claim();
+    _isOn = true;  // set before begin() to prevent double claim
+    if (_peripher_power) begin();  // re-init display after power was cut
   }
   display.ssd1306_command(SSD1306_DISPLAYON);
 }
@@ -32,7 +30,9 @@ void SSD1306Display::turnOff() {
   display.ssd1306_command(SSD1306_DISPLAYOFF);
   if (_isOn) {
     if (_peripher_power) {
-      if (PIN_OLED_RESET >= 0) digitalWrite(PIN_OLED_RESET, LOW);
+#if PIN_OLED_RESET >= 0
+      digitalWrite(PIN_OLED_RESET, LOW);
+#endif
       _peripher_power->release();
     }
     _isOn = false;