Sometime back (Feb 2022) we were seeing an issue with some of the Xiao Expansion boards appearing to short out the on board 3.3v regulator when plugging in the Xiao BLE.
Here is one such thread from Feb 2022
In my case I was just plugging the Xiao BLE into the expansion board, usb connector the to Xiao BLE. (no other power source, battery etc)
The modified broken boards worked for my purpose, just using the SWD interface, but now I find I’m needing to run some I2C functionality, which does not work when the Xiao pins 4/5 are connected to the broken board.
Has the expansion board been modified to help eliminate this issue? If so, is there a board rev number we should look for?
If not redesigned then it sounds like the safe bet is to not connect the Xiao BLE 3.3V pin to the expansion board. Is this the “official” answer.