Review on Seeed Studio Seeeduino XIAO SAMD21 Cortex M0+ Board: 100% Arduino IDE Compatibility, Breadboard Mountable, USB Type-C (3pcs) by Scott Ward

I have an Arduino IDE for Mac. I have downloaded all necessary files for these boards. We managed to chat and upload the sketch to the first board. It started and worked fine. I tried uploading another sketch to the same board and the PORT was gone. No more contact could be made with him. Tried the second board. I was able to upload the sketch to the board with no problems. I tried uploading another sketch to this board and the port disappeared just like the first board. Tried the third board. Same problem. Now I have three boards that I can no longer communicate with. The boards turn on but can no longer communicate with them. UPDATE 2/23/21 IT IS FOUND THAT THE BOARDS COMMUNICATE WITH THE IDE WHEN THE RESET CONTACT PULSES QUICKLY TWICE. IF IT PULSES TWICE, A USB CONNECTION FOR THE BOARD APPEARS AND CAN BE CONTACTED AGAIN. A SINGLE RESET PULSE APPEARS NO USB PORT. I will keep experimenting with these boards.