No screen output, is there a way I can salvage it or is it dead?

I bought a defective 4a from ebay. The owner (allegedly) said it stopped working when it got some humidity in his pocket. I got it and foolishly didn't even test it before tearing it apart. Anyway, I took it apart, saw no humidity or water damage, washed the motherboard and connectors with alcohol and built it back up. After charging for a bit it turned on, but there is no screen output. Is there a way I can salvage the screen or is it dead for good? How can I know?