IPhone :: 4 Screen Won't Show, Is It The Battery

My iphone 4 screen wont light up. I press the power button and it just flashes and shows me the screen. But the phone is on. The screen is completely black though. the person i got it from replaced the battery saying it was the battery that was causing the issue. Then it happened again. And someone recently said it was the new battery that was the problem. it could be fake or a bad battery bought off of ebay. which is where i bought the iphone from. So maybe the person bought the battery off ebay as well. But to summarize my issue. I push the power button and it flashes the lock screen. if i push it again nothing happens, because thats when the screen is supposed to shut down so you can save battery life like it normally does. But pushing it to show the screen only makes it flash, it doesnt stay lit. could the battery affect it like this? should I buy a new one and try it out? if so, does any one know of a genuine battery I can buy? one that wouldnt fail me?

Info:
iPhone 4, iOS 5.1.1