iPhone 4 screen is black after replacement

I recommend connecting your old screen back on your phone. If old works, then new one is faulty and needs to be returned to vendor.

"I had the same problem. This is how I fixed it.

Remove the LCD cables, Place some windex on a napkin, wipe the connectors. There might be some windex left on the connectors, so get a dry napkin and dry off. Make sure you put back the conncetors correctly and it should work. It did for me. I only removed the battery to avoid a short circuit. and the plate that covers the LCD connector so you dont have to tear the whole thing apart. GOOD LUCK. Hope this helps some of you."

"Resetting the phone is your best bet. You can do this by holding down the sleep/wake button and the home button at the same time for about 5-7 seconds.

You can also simply disconnect and then reconnect the battery. We have to do this quite a lot when testing LCDs internally."

"Mandy, your symptoms sound similar to mine. Have you tried cleaning the LCD connector with a light application of Windex, as in this post above from Luis:

I had the same problem. This is how I fixed it.

Remove the LCD cables, Place some windex on a napkin, wipe the connectors. There might be some windex left on the connectors, so get a dry napkin and dry off. Make sure you put back the conncetors correctly and it should work. It did for me. I only removed the battery to avoid a short circuit. and the plate that covers the LCD connector so you dont have to tear the whole thing apart. GOOD LUCK. Hope this helps some of you.

I also posted similar info above with a few other tips."

"Hi guys, my iphone 4s is in a similar condition. I self-repaired the screen and everything fired up normally, then a few weeks later it went into the black/grey screen described by all of you. The repair took about 5 hours, as I was very cautious with ensuring all components were connected appropriately and cautiously.

I actually took the phone to the Apple store to have them look at it. First time around the worker said that nothing could be done, so I went back a few hours later. The second person was more tech savvy, and he got the phone back up and running. He mentioned that the phone screen appeared to be replaced, and mentioned that some of the connections appeared to be loose and slightly damaged. As I mentioned, I had been very gentle with this repair, as I assume most of you were as well. However, these are very delicate connections and potentially we have damaged our connections during the repair. This could be caused both at the LCD/digitizer end, or on the board. I notice no one has mentioned that a board replacement may be the fix for this. I am considering purchasing a replacement board to ensure that this isn't caused by a slightly damaged connection on the board side. I suggest using slight magnification to inspect both the board side and LCD/digitizer side of all of your connections for any damage to ensure that your iphone problems aren't being caused by damaged hardware.

Hope this helps a few of you out there in Internetland!"