My iPod Touch screen wont light up, CRISIS AT HAND!

I recently cracked my itouch screen and bought a new one on amazon and i followed the guide and attached the LCD and digitizer completely fit, and i put all back together but my itouch wont even light up, and it randomly turns all white only when i hold the power button but when i let go it goes back to being normal ive tried the power and home button thing but it doesnt seem to work ive triple checked to see if any wires are cut or loose and it lights up the most when i point it downards and press the power button