Issues on iPhone 4 Reassembly

I recently ordered a new front screen for my iPhone 4 from iCracked that came with a kit and instructions for repair. Last night I spent around 2 hours disassembling and reassembling my phone. I didn't encounter any problems and everything seemed to fit together correctly, but the speaker feels loose and because of that, I can't slide the back cover back on. I'm sure that can be fixed by going through the process again, although I'm not sure how it happened as the other pieces fit properly.
Importantly, when I turn on the device, the backlight comes on, but it is almost entirely black except for a few horizontal green/yellow stripes along the sides and a small, dark, blue fingerprint shape in the upper-right corner. I haven't been able to find any information about how to fix this online. I can slide to unlock and the unlocking sound registers, but I can't do anything else. The home button seems to be nonfunctional and I can't turn to phone back off without disconnecting the battery. I've tried switching between vibrate and ringer, but the vibration does not register.
The phone is essentially useless at this point, so I'm considering taking it in for repairs or a replacement. Is there anything I can do myself or common errors that I could check inside the phone, or would it be best to leave it to the professionals?

Thanks!