Sorry if this post came up more than once, my internet kicks out every time i submit.
If the phone vibrates, its got power. Its 1 of 3 things.
1. The LCD you bought was shipped broken, the testers are cheap. Wouldn't be bad if it saves you $40/$50. Please don't buy cheap screens. You'll notice the difference in the display.
2. The flex cable is loose. Take it apart, disconnect and reconnect the cables and make sure they're snapped down. They should snap, sometimes there's a little yellow tape on the LCD that gets moved from holding down another component. Make sure the motherboard and the cable itself has nothing in or around it.
3. You probably ruined the LCD flex while installing the glass. Those cables are thin, and can easily be ruined. Hopefully its not the case. I've been repairing phones for years, i've accidentally ruined a few while rushing.