I agree with the post above. If your LCD is dim then it is caused by disassembling the device without power it off. If you can't do a hard reset it is most likely due to the power flex being severed. This is common. Also 1 tip if the LCD doesn't light up take it to a microsoldering guy and he can fix it for you. This has happened to me before and they were able to fix it at a computer repair shop. Good luck.
Plug the iPad into iTunes on the computer and Put the device in DFU mode and restore it. Hold the home button and power button for 10 seconds exactly at 10 seconds remove the power button but continue holding the home button until you have a black screen and iTunes recognizes it in recovery. Restore and good luck
You can use a circuit writer pen to connect those to points. Circuit writer pen can be bought at Fry's Electronics or at Radioshack. Take your time by practicing on paper to get a perfect small dot. Follow the picture above.
Use 99.9% icopropyl alcohol to clean the logic board. Could be moisture on the board. Check this out from Frys.com Get a brush that doesn't conduct electricity like a nylon brush from the store. Dip some alcohol on the brush and scrub the board. If it doesn't work try a new charger flex/battery and if it doesn't work there are companies that can microsolder. Check my webpage for more info.