Hey jaja,
There is only one button on the Dragino Shield.
The button is outlined here:
http://wiki.dragino.com/index.php?title=Yun_Shield#For_v2.x_series
And instructions for use of the button here (including reset):
http://wiki.dragino.com/index.php?title=Yun_Shield#How_to_reset_the_Yun_Shield
I have a Dragino Shield on an Arduino Mega, its an absolutely awesome combination. The shield did take some fiddling to get going. The wiki page has all the info you need, and their their support team is very quick to respond if you contact them.