My iPhone's screen went black and now it won't turn on

Hi Trini. There are a few things that could be causing this. Because you bought this used, we don't know the history of the device. For example, it may have been water damaged in the past, or suffered various falls and impacts. It may also have been repaired.

So without knowing any of this, here is what I recommend:

• You need to open up the phone and take a look inside. Use this guide.
• Compare what you see in your phone to what you see in the guide's pictures. If the phone has never been worked on, it should look pristine.
• There is a water indicator (look at the image on step 13, next to the orange circle). If it is red, then your phone has been in contact with water.

Depending on what you find inside your device, you may just have a damaged screen. However, there may also be some problems with the logic board and that would require a repair shop to do a proper diagnostic (one that does micro-soldering repairs would be even better).

Follow the steps and come back and comment on this answer with your observations.