I think I've killed my pro mini clone

So I've recently taken the dive into the arduino world, I bought a few generic "pro mini" with the 32u4 off aliexpress website.

They've been working great and my project has been growing peripherals - a couple i2c devices and a one wire temperature sensors and a key input and some PWM driven LEDS. (Single modules on resistors as place holders for 12v strips via power transistors).

I'm not sure if it's because there were so many wires but it stopped working one upload, the screen stayed fuzzy and pixelly like it does during boot up (i2c oled). I thought it was just the board so I plugged a fresh pro mini i soldered up with headers and it did the same thing - I'm not game to try it with my last one which is detected and works however the two busted ones no longer appear on the virtual com port.

Only one LED on the busted boards Comes on - usually there are two and one flashes green.

I'm not sure what I've done I didn't do anything consciously - could all my wires have shorter or done something ? Since there's no dedicated FTdi I'm wondering if it's just bricked or something?

How can I diagnose it? I have some USB to serial converters of different type - can that be used to program it or anything?

Remove all peripheral bits and load Blink. If you cannot get it to work, let us know what happens.


Hi, Thanks for the reply. I've tried taking the board out and connecting it bare to the USB port only, however it fails to be detected as a serial device anymore - both the original board and the replacement that also stopped working, my third board comes up just fine in the IDE. There's only one red LED, usually there's two and I see a green on flicker too as it starts up.

Looks like the board is damaged. Electronic development with pieces of wire all over the place is well known to destroy parts if there is a short or wrong connection.