I've read that what I'm experiencing isn't an error, but I wasn't seeing that before and my sketches aren't working when I see this. I'm an extreme novice with this stuff, but trying to learn the ESP8266. I was able to use the AT commands no problem in the beginning, but then I tried a tutorial showing uploading blink onto the ESP8266. I was able to do that, but now I don't know how to get back to AT commands. This tutorial on installing firmware seemed very promising, but I was getting "esp8266 chip efuse check error esp_check_mac_and_efuse" errors. Before trying to upload the firmware, I had uploaded a blank sketch onto the ESP8266. After the firmware stopped working, I was curious if I could upload the blink sketch again, but now I'm seeing the "hard resetting via RTS pin" after uploading, and the blink sketch doesn't work. I'm 99% sure that I was previously seeing a soft reset message after uploading the blink sketch.
Now I've ordered serial adapters, but I still really want to be able to do it via my mega.