I spliced two PWM fan tach wires and connected them to a single ESP8266 GPIO pin. Since I tried powering this on I couldn't get the ESP8266 back up and running, even after disconnecting the splice again.
It's probably important to point out that the whole thing was working as expected before I spliced the two tach wires into D2. With only one connected I was able to read the fan speed and control both PWM fans correctly.
Did splicing two PWM fan tach wires to a single ESP8266 GPIO pin fry my ESP8266 or did something else kill it? Like maybe I fumbled and accidentally shorted a 12V line to a GPIO pin or the 5V line while plugging stuff into my board?