How to fix an iPhone 3g screen?

Recently replaced an iPhone 3g LCD screen because the backlight wasn't working, but apart from that worked perfectly fine. After replacing the LCD, the phone goes to a half grey screen, half vertical coloured lines and then turns off after a few seconds. The backlight appears to work now but I can't continue to a normal startup. Is the LCD screen defective or what?
Any help would be great.

Since it's the new screen for the iPhone 3g, it might be the problem of the displayers. We're not sure about that, so you'd better send it to some repairing stores and find out the real issues.
If this connect to the hardware issues, you will have to replace them with too much money, and you might consider buying new iPhone, and maybe iPhone 4s

Oh dear… I did the same thing when I tried to replace the LCD. I ended up damaging it all. I would not recommend trying to fix it yourself again, you could end up damaging even more. I would send it to a professional company who will be able to repair it for you cheapily. If you don't go with apple and go with a company like this: http://www.phone-hub.co.uk/ It will save you a lot of money.