Troubleshoot Arduino LCD 16 x 2 shield I tried to assemble Adafruit's Arduino LCD 16 x 2 using the instructions RGB LCD Shield: Control a 16x2 Character LCD using 2 pins - Assembly  without any success. 

After assembly, I uploaded the HelloWorld example sketch on to the Arduino. The shield doesn't seem to be working. The LCD didn't turn on. 

If I push back/press the LCD it turn on. Any idea on how to troubleshoot this?
By visually assessing the pictures, the issue seems to be due to poor soldering job.

You should try re-heating the soldering joints and make sure they are clean. There could be dry joints that may not be conducting signals.

Also you should upload pictures to your question post, not as an answer.