[Q] Screen Replacement Leads to Unbootable Phone topic

So I recently cracked the screen on my HTC One m7. I bought a replacement screen and front housing. The screen was so far beyond repair that I couldn't shut off the phone prior to starting the replacement. I tried waiting for the phone to die but after two days I became impatient and did it anyway (essentially the phone lost power when I disconnected the battery). After transferring all parts into the new housing and being what I though as diligent putting all parts and connections back in their place, tried to power the phone back on. all that happens is that the back and home buttons flash and then I hear what sounds like the audio for when the phone powers on. The screen stays black and then phone doesn't technically turn on. I know this because I have missed messages and the green led light would be flashing if it was. Therefore, at this point I'm not certain that the new screen works or if I've connected it right. I've tried the numerous boot tricks with the volume buttons, nadda. I have had the phone on a charger for a full day and the same problems. (Disclaimer: I don't have the original charger, but I have been using this one for a long time). I do see the red charging led if I wiggle the charger in the input, but also just recently I saw a green led when doing this, which when the phone was working was a sign that it was fully charged. If anyone has a solution to my problem that would be great. I'm also interested on what's wrong, why this is happening, what might have caused this behavior? What do the flashing home and back buttons mean?