The AT commands worked great on my ESP8266 ESP-01's when I got them. Then I tested uploading sketches onto the chip and ever since I haven't been able to get the AT commands to work again. I've tried the following tutorials for loading firmware.
Tutorial 1 gives the following errors
5-chip efuse check fail
[ESP8266Loader_spi][espDownloader.py][line:468][ERROR]: ESP8266 Chip efuse check error esp_check_mac_and_efuse.
Tutorial 2 worked, but I have not been able to get AT commands to work after loading it. The firmware in the example is extremely old. I tried a different version of firmware from the site provided in tutorial 1, but that didn't work either. The particular firmware used in tutorial 1 was in a different format and was broken up into multiple bin files. The firmware in this example only has one bin file. I've tried changing modes, but that hasn't worked yet either.