No more working correctly when plugging in USB cable

[senti1000]

Hi all,
I've found a strange problem with my MeCreator2. The printer works just fine when printing from SD card.
The moment I plug-in the USB cable, things are going to get weired.
First observation:
I was stunned when I noticing the printer starts working as soon as I turn on my PC that is attached via USB, EVEN THE MAIN SWITCH IS OFF!
It seems, the electronics is optionally supplied by the 5V coming from USB.

Second observation:
Whenever I plug-in the USB cable, the extruder won't heat up anymore. Actually the "to be" temperature stays 0. This is also the case, if I print from SD card. In contrast to this, the bed heater works correctly. As soon as unplugging the USB cable, everything works as expected.
This is not only odd but also causing real trouble, because it (most likely) prevents me from operating octopi on a raspberry.

Anyone having the same problem or (even better) already figured out how to work around this problem?

[senti1000]

Ok, finally the problem is solved.
For whatsoever reason, you'll need to take out the SD-Card when connecting the USB. Vice versa, when printing from SD-card you need to unplug the USB. Now that I know, I can cope with this. Eventhough its a weired behavior.