iPad 4: Black screen, no charging and not powering on!

I have had an iPad 4 for a while now, I decided to start using it again. I had known that the lightning connector stopped working last time I had stopped using it, and I also remember turning it off at 50%.

When I tried powering it on few days ago, it didn’t turn on or charge. So, I decided to replace the lightning connector thinking it had finally died and the battery had probably drained itself. I used the following iFixit guide: iPad 4 CDMA Lightning Connector Replacement I was actually able to replace the connector fairly easily following the guide (kudos for that!)

But, when I tried to turn the iPad back on, it doesn’t turn on nor charges. I have tried the following things:

1. Different charging cable.
2. Different wall connector of the charger (the thing that slides into the iPad charger).
3. Charging using a computer + iPad’s cables (in case the charger was entirely broken).

None of these result in any response from the iPad, no battery symbol, no apple logo, nothing. Would anyone have any suggestions for me to try to debug this?

Thank you!