Hi，Dreamer_mos ：

Can you take a picture to show your test enviroment? As you said, boards gets hot, are VCC & GND shorted?
　

这个R9是没有上件的，即GPIO12在模组上没有上拉。是否是外部接了其他设备？

As you know, we may have caps on EN or GPIO0, so there would have a slow rising edge on such signals. I suggest you can use a oscilloscope to have a test which would help you understand this a lot.

Will pressing EN and GPIO0 buttons can make the board into downlaod mode?

I guess there would be some timing issue about EN and GPIO0. Suggest you can use oscilloscope to measure EN and GPIO to make sure GPIO0 keeps low when EN goes high at boot mode.Thanks.

Hey, you can post your schematic here and we can help to have a double check.

1)No need...
2)It is 1.8V on-board configured. No external resistor needed. But take good care of GPIO12 whose power-on status decides the supply voltage for flash. And also, we can configure registers to change the voltage level after power on...
3)Please post your schematic here, thanks...

Sorry, but what does SCL mean?

You can consult your supplier, but from my own point, you can use the Pin labeled "GND" as GND.

Hey, you can check link https://docs.espressif.com/projects/esp ... vkitc.html to see "Note on C15" to confirm if C15 exists? If yes, please remove it.