I have a Wemos d1 mini, and when I upload nothing or anything to it, the built-in LED always lights up and the serial monitor gets a lot of garbage at every baudrate. I have supplied it with 4 AA batteries and the board has a built in voltage regulator of 3.3V at the 5V pin. enter image description here

The Wemos d1 mini contains the esp8266 chip.

Please help me! I have searched everywhere. This just happened all of a sudden, the board was working perfectly fine before too.

  • do you have anything hooked up to the pins?
    – dandavis
    Jun 8, 2017 at 2:27
  • No, nothing is hooked up besides the power cables. Jun 8, 2017 at 2:28
  • Garbage on the serial port when you power the board up or otherwise reset it is normal. It's the bootloader boot messages at a strange baud rate. You can ignore them.
    – Majenko
    Jun 8, 2017 at 9:22
  • @NathanRamanathan - You have power cables and USB? It will draw power from the USB, you don't need external power too. Like Majenko says ESPs always dump garbage on start-up, so it might be OK. Have you checked you have the Reset switch in the correct place? Have you grounded GPIO-0 (not D0) during boot up and corrupted the firmware? Jun 8, 2017 at 11:43
  • Yes, Code Gorilla. You figured it out! I might have accidentally grounded pin d3, GPIO-0, during boot up.😞 What do I do? I never heard of reflashing a wemos D1 mini. Jun 8, 2017 at 14:21

1 Answer 1


Three words. "You Bricked it"
Before you go surfing on the web for days and days, I'm just going to say the module is bricked. I've been there and found out that you should never use these devices on breadboards and with funky power sources. There is this chip within the module called eFuse, which is basically an electronic fuse that's really easy to destroy. Just use the Arduino YUN or other certified or Chinese clonable modules. Those Italians are smarter than you think. That's probably more reliable because you won't have any power issues or frying issues.

I'm also assuming that you are getting a fatal exception (0) in the Serial Monitor. In that case, your module's death sentence is officially sealed.

Congrats. :(

  • For me, this was not true! I was able to "revive" the ESP-01 by simply flashing it again using Arduino IDE. I was getting the same message from the Serial Monitor prior to this, after I've tried flashing new firmware.
    – hakazvaka
    Feb 4, 2021 at 20:20

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