How did I miss this question?
For iPad mini no power---
1.) It's not the charge port if there is no visible damage to the port
2.) It's not the battery---unless you just changed the battery like the OP--bad batteries are a dime a dozen--you'll need to rule that out. For everyone else, it's not the battery
3.) Have you opened your mini recently for another repair? If so, it could be a missing filter next to the battery connector---look hard for pry damage near the battery connector.
4.) If none of the above, then it is going to be non-Apple charger damage to the charging ic chip U2. This sucker is used in every lightning port device and is very susceptible to unprotected voltage fluctuations. It can be replaced as a difficult board level repair.
I wrote more detail about a lot of this in my Ultimate iPad Mini repair blog:
http://www.mendonipadrehab.com/entries/general/the-ultimate-ipad-mini-repair-post