Hi guys,
I seriously need your help and experience with this:
I have a SIM900 module like this (http://www.alibaba.com/product-detail/MINI-V4-0-Wireless-Data-Transmission_60097115635.html) bought in Mexico. Worked fine, but I needed to get into a firmware update, which was performed well (message Download done at the end).
The update was performed directly, not through arduino.
The problem arised just after power it Off and On again. Not response at all to any AT command, at any standard speed. All the wiring and power supply, OK. I have serched around the internet and some folks have found similar problems after firmware updating, but no any solution have been posted.
The module looks like frozen, and I have no idea how to restart it or force it into a boot mode to get it into a new firmware update.
Already lost in your opinion? 
Thanks