MDBT42Q no polarity protection?

I've just got my first MDBT42Q to try play with, after all customs and postage process which was an extra effort, during first time i wanted connect it I probably fried it.
I know there is written warning to check polarity, I wanted to connect it via usb/ttl converter as my macbook doesn't support ble. I don't know how I did it, I checked wiring few times and finally connect it wrong.
I know, my mistake, but from my point of view board for 20GBP should have protection against wrong polarity. I remember I made wrong connection with pico, but there is rectifying diode, I changed it and pico is still working.
It's pity I can't play with ble again, MDBT42Q is fried, and Bangle.js I ordered can't connect with any of my 4 computers (they don't support ble, also few dongles USB I have). Unfortunatelly again I have to make step back and come back to arduino for another few projects, my next attempt to switch to espruino failed.

@bigplik, you are talking Espriuno MDBT42Q breakout board?

...that's why I usually by 2 or more things at once if they do not cost a fortune... Looking and checking twice and still connecting the wrong way or a powered wire (pulls and) brushes over the setup is something possible to happen. Sorry for that it happened to you (too).

I'm not sure you really want to pin the failing of transition from Arduino to Espruino ecosystem... At worst I would consider it a delay...

yes, it could be a delay, but I need to finish 2 projects right now, waiting for espruino with customs in my country is 2weeks +, so have to choose arduino again :/

Argh, sorry you've had problems. Maybe you could try powering it via 3.3v and see if it still works?
While the board itself doesn't have reverse polarity protection, I believe it's the voltage regulator that most likely gets blown up, not the chip.

Usually it's pretty robust. I just connected one backwards to a LiPo here to see what would happen and the voltage regulator started smoking, but the board still worked when I turned the voltage back around.

I remember I made wrong connection with pico, but there is rectifying diode

There's a rectifying diode on USB since you have the voltage, but on the battery pin it has to use a FET (because you can't afford to have the voltage drop). There wasn't enough board space on the MDBT42 to fit that in unfortunately.