How many times should I click the Reset button to put the Arduino Nano ESP32 into "bootloader mode"? What do the color changes of LED lights represent? Such as green; red and blue segments illuminated at half-brightness.
Hello @feei and welcome to the forum! 
You can find all the answers here. It's useful to update your board once in a while as new bugfixes could be available since the last full reflash.
Hi, please help me solve my question
Sorry, got the links mixed up! What I wanted you to read (first!) was from the Nano ESP32 Cheat Sheet, especially the section on Bootloader mode. The link I sent earlier was for reloading the bootloader, and didn't have the introduction I thought it had... 