Wemos D1 Mini Pro Schematic Online

The D1 Mini Pro uses a USB-to-serial converter for programming and serial debugging. Early versions used the (Silicon Labs), but later revisions and clones adopt the cheaper CH340G (WCH). The schematic highlights:

The ADC on the ESP8266 is notoriously non-linear above ~1.0V and expects a source impedance of less than 10kΩ. If your schematic shows a 1MΩ voltage divider on A0, your readings will be garbage. Wemos D1 Mini Pro Schematic

No Power: Check the voltage at the output pin of the LDO regulator. The D1 Mini Pro uses a USB-to-serial converter

The Wemos D1 Mini Pro does not use the raw ESP8266EX chip. Instead, it uses a module, which is a metal-shielded PCB containing the ESP8266EX, 26MHz crystal, and 16MB flash RAM. it uses a module