Hello guys!
First of all, I'm not really sure if I'm posting on the right forum, but if I'm not, I'm sorry. I may be thinking that the problem is related with the microcontroller.
So I've been tinkering with my XBee Series 2 modules, buttons, LEDs, buzzers, sensors (DHT11) for the past few weeks, together with my Arduino Uno R3s and a single Arduino Pro Mini 5 V 16 MHz for a wireless sensor network project. I've been working on them connected to the computer ever since and now I would like to test them as standalone modules. So far, they have been successfully working, like for example I press a button from a node for too long, afterwards an alert will be sent to the coordinator. Upon receiving the alert, the coordinator broadcasts a message to all other nodes in the network to activate their buzzers.
However, as I connected power to their barrel jack connectors (except the Pro Mini which is still connected to the PC through a UART adapter since I have no batteries yet), trying to press the button results to nothing. Moreover, a router XBee from a node keeps on blinking, which does not occur when its Arduino is connected to the PC.
What should I do? Thank you for anyone willing to help! IF there are any unclear statements, please let me know. I'm still on the way to making small discoveries with the Arduino and XBees. 
Note: A WSN is a wireless sensor network. It is mainly composed of a sensor node (composed of radio device, processor, sensor and power unit, typically a battery with some additional components such as regulators and etc) and a network sink (composed of s processing unit with some interface software and a connected radio device). A gateway may also be included as a part of the system to make the info available elsewhere such as the Internet. A sensor node gathers information from its environment through a series of input signals from the buttons or sensors. These are processed and wirelessly sent through a radio device to the network sink.