I recently had to update my Xiami Yi small ants camera firmware since it was not compatible to the app anymore. Step one is to find out what Version do you have. On the back of the xiaomi small ants you can find a short code where the 3rd and 4th digit tell you what version you got.
CN, ZP, ZH is for China and HongKong – Download Firmware for Xiamo ants camera
All the rest is international – Download firmware for Xiaomi Ants camera
Current version (11.03.2015): 22.214.171.124A_201602241619
The manuals can be downloaded on the same website but to sum it up:
1. Format you SD Card
2. put the „home“ file on it.
3. Plugin the SD Card into the camera and power it up.
I tested it out with CN and US version and i didn’t bricked my camera. But I would not say that it can’t happen to you.