HI there,
In the tools menu You can set it debug level and it will output some info when it resets.
Unfortunatly there isn’t any indication other than the current program will stop.
I used the factory firmware on the S3 wiki page.
Extracted it to a folder and ran the Bat file with the S3 connected while holding the boot button down. ( I do get a windows chime port found), also worth noting if at this point I have Arduino IDE open and I open the serial monitor and I set baud rate to 115200 then Close and open the serial monitor again, the monitor (the Xiao spits this out to the port)
ESP-ROM:esp32s3-20210327
message (it’s in bootloader mode) and you can keep doing it.
When you press and hold the BOOT key while powering up and then press the Reset key once, you can also enter BootLoader mode.
After the factory firmware is restored it IS back to the touch demo when it was new.
press the reset button and I get a message
"[ 255][I][esp32-hal-psram.c:96] psramInit(): PSRAM enabled"
BTW the core Debug level is set to “None” in the tools menu.
HTH
GL 
PJ 
In short
- Reflash the Xiao with factory BAT file , then verify. (touching pins lights LED)
- go back to Bootloader mode with Holding the Boot button and plugging in USB
- flash the I2S code to Xiao and be happy again.
