Arduino dfu not found after hard reset

I’ve reset my esp32 nano board from arduino and erased flash memory with esptool and now when I try to send an arduino programm i got the error : No DFU capable USB device available
Failed uploading: uploading error: exit status 74
Moreover my board is now detected as an ESP32 Family device instead of arduino nano esp32…
Also the LED is constantly on and purple and the board start connecting/disconnecting in repeat as anything is done

I'm not familiar with your board. Does https://support.arduino.cc/hc/en-us/articles/9810414060188-Reset-the-Arduino-bootloader-on-the-Nano-ESP32 help you to solve the problem?

that was pretty efficient in fact
thanks