Just replaced broken screen on 5s, now neither screen is working.

When I initially installed the new screen, the screen went on (blacklight) but was black. With this happening, I then did a soft reset. After the soft reset, I had nothing on the screen. It wouldnt even go back to the backlit blank screen. I think proceeded to put the old screen back in, assuming the screen was either defective or damaged during service, and there was nothing as well. I am now stuck with an iPhone 5s, with a customer waiting, that does not work with a new screen or the old screen. Ive tried virtually anything, but would love some pointers to try and fix this. I'll be checking back on this throughout the night, any responses are greatly appreciated.