Suddenly Can't upload any sketch on Pro Mini 3.3v


Is it possible to fry Pro mini 3.3v (Sparkfun), by connecting it to Raspberry pi (i2c pins) ?

I have connected Pro Mini and Pi Zero W, like so:

  • A4(SDA) -> GPIO23(software SDA)
  • A5(SCL) -> GPIO24(software SCL)
  • GND -> GND
  • 5v DC connected to Pro Mini RAW pin, and raspberry 5v pin

I was trying some sketches to understand how does the i2c connection actually works and after a quite few tests, suddenly I wasn't able to upload any more sketches to Pro Mini :o I didn't even touch any wire on the breadboard...

I've tried a lot of code (on both, Pi and arduino) while testing and probably most of it was wrong. But for my understanding - both modules uses 3v3 I/O, right? So I shouldn't burn anything (at least not this time :smiley: ), right?

Using Arduino IDE v1.8.5 I can upload bootloader, but I get errors while uploading sketches.
Using newest Arduino IDE (beta) I can't even upload bootloader.

Should I throw another arduino to the garbage can, or is there anything I could try to get it alive?