RAK 19007 + 4631 reverse polarity damage - how bad?

I was building my RAK device and despite being warned, I plugged in a 4.2V Li-ion battery with reversed polarity. I had checked the polarity before, but took for granted the fin on the JST would only go in one way. The JST was reversed.

I immediately smelled some light burning and unplugged it. It took me maybe 30 seconds from plugging in to unplugging it.

I was worried I had fried the board as many posts online suggests it is instant irreversible damage.

I fixed the JST connector and the battery powers on the board when plugged in correctly and I can send/receive to my other devices in the house no problem. I see blue and green lights blipping every few seconds. I haven’t tried other nodes as I don’t have any in my area. Would this affect my range?

I plugged in in via USB as well and it powered on with the red light on.

So it seems like it is working?

But not sure what else I should be checking.

Are there any other function tests I should consider? What else could be damaged from a reverse polarity plug in?

Do you get any output on the USB port?
What firmware was flashed on the RAK4631? Blinking green and blue every few seconds doesn’t look normal.
Worst case you have destroyed the charger chip and maybe the voltage regulator and the RAK4631 is rebooting permanently.


Thank you for your response. The Firmware is the latest beta being: firmware-rak4631- .

The blue light only comes on for a moment when I power on. I havent seen it much so hopefully that is okay.

I have been able to charge the battery while the battery is plugged into with the JST, and a usb c is plugged in.

Are there any function tests you can recommend to determine if I have anything damaged?

Everyone online says it should be instant damage but everything seems to be okay. Just want to know what to test to know if something is damaged.

Seems you were lucky.
Just observe the board while letting it run for some time if it behaves weird or reboots without reason.