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.
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.