I don't remember what I did to it. It has been at least a year.
AT+GMR
AT version:1.0.0.0(Apr 16 2016 13:02:45)
SDK version:1.5.3(aec24ac9)
Vowstar Co.,Ltd.
Build:1.5.2.0 Apr 25 2016 18:52:23
OK
I have another ESP-01 module that I bought at the same time.
It has the Ai-Thinker firmware which I do remember was what originally came in the module.