I don't know why these programmers don't have a button. But you need to solder a button to connect one of the pins to ground before you can flash the esp01. Luckily I had something in my spares basket. I didn't read the description carefully so I had trouble flashing before I went back and read the review and problem description. You need to change it as soon as you receive it. I would deduct more stars but I think it's a design issue with programmers like this.
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