ESP32: Trying to revive it. No com port only a blue light blinks once.

Hi @scsiraidguru,

  Others may be able to help more, but I haven't had a 'bricked' ESP32. However, I have previously noticed that Espressif provide firmware images, and there are instructions on the web, probably by Espressif, as well as YouTubes, on how to reload the firmware, so a few minutes Googling should provide some suggestions.

However, I am somewhat dubious whether 'bricking', by overwriting the firmware, is your problem.

"My workstation doesn't show a COM Port for it." leads me to wonder if this is a different problem. ESP32s normally have a USB handling chip, which in your photo will be the square black chip with about 28 pins, next to the USB socket, probably with a number like CH340 or CP2102. Intuitively, I would have expected your workstation to 'chat' directly with this chip, to negotiate and initialise a driver on the workstation, before the ESP32 and its firmware got involved.

Furthermore, downloading firmware is essentially the same process as downloading a user program, using the USB cable etc. so I am not optimistic that you will be able to do that, before you have persuaded your workstation to initialise the appropriate USB driver, etc.

Although the board looks completely disconnected, make sure there are no links to any of the pins, as some ESP32 pins are checked for being high or low at power up/boot time, with different results, depending on what it finds.

Best wishes, Dave

@scsiraidguru What were you doing with the esp32 before you got the symptom of no COM port?

You are talking about two different manufacturers, ESP AND Arduino. Don't confuse them.

I have had several dozen cases of what you have, and every time the board was OK. It's just the way it is. I have found some cases where I have to close the serial monitor, some I have to reload the IDE, very rarely re-boot, but NEVER have I had to re-flash the board.

I tested the 3.3V pins.  1.45 to 1.66V out of all 3.   

Hi @scsiraidguru,

RE: I tested the 3.3V pins. 1.45 to 1.66V out of all 3.

Sorry, but to have a chance of me understanding a description like that, I need a lot more contextual information, preferably to the point of pointing at a referenced schematic, plus defining what conditions you were testing and which pins, etc.

On the face of it, ~1.5V on 3.3V pins does not sound healthy, but it might have a simple explanation, including it might be a floating input or an oscilating output.

In addition, if this problem applies to a single ESP32 board, with an AliExpress price tag of about US$3, there comes a point, where replacement is  the obvious first option. I realise that sometimes, a 'full forensic' approach to find out the whys and hows is justified, but this also implies the 'forensic sleuth' examining the board has both the test equipment and knowledge to achieve it, neither of which come cheap in the commercial world. Of course, we have some helpful and knowledgeable contributors to the forum, but there are practical limits.

Best wishes, Dave 

I like to try to revive stuff.   Yes, I know they are cheap.  I have over 12 Arduinos now.  I revived my Mega 2560 Wifi.  I thought I would give it a try.  

@scsiraidguru Do you buy 'dead' boards, or do you accidentally kill them?

No idea.  This board connects to a powered USB hub not a power pack.   Never had it working.   I could have been a dead board.  

@scsiraidguru I am confused, in order to program the board, it has to be connected to a computer via USB, no need for a hub.

BTW, when are you going to learn to use the Reply link?

@zander I keep forgetting reply is there.   I have many USB devices.  It is easier to plug in and off a hub.  I once shorted a motherboard removing the plugs.  I figured it is bricked.  I thought it would be interesting to try to revive it.  

@scsiraidguru Maybe it works.

@zander I wanted to reflash it to see if I can get some life from it.  So far, USB connection doesn't even find a port when it is connected in device manager.   Some one said to connect a multimeter to 3.3V and ground.  I don't get 3.3V about half.  I looked at the board under a magnifying glass and didn't see any damage.  I tried both Ubuntu 22.04 and Windows 11

@scsiraidguru IIRC, there is a procedure that involves at a minimum holding down the reset button, and I don't recall the other steps. Try searching the Espressif doc library for flash but of course that will give a lot of false hits for Flash memory.

@zander It took 2 months to find good docs on the flashing the Mega 2560 Wifi.   I wondered if Bill knew how to do it.  He took a fall and his mom is injured.

@scsiraidguru I know about Bill and his Mom, I was online when Bill reported it.

Are you trying to upload the AT firmware?