Replacement battery lasted two days

Having done several battery replacements in other IPhones over the years, when my daughters phone wouldn't take a charge and went dead I ordered a replacement battery. It arrived and I installed it, no issues. The phone powered up, we went through the battery conditioning cycle (discharge to 10% then charge to 100%). No problems there. Two days later the phone doesn't see to be taking a charge again from a known good Mfg cable, it discharges over night instead of charging and is now dead. I went back into it to check that a connector wasn't seated right ... All good there. Could I have gotten a bad battery?

Ifixit, does this happen? All other parts and repairs have been great!

Where should I look? What should I consider? New battery bad? Dock connector bad? I inspected the dock connector port and lightly brushed it with a soft bristle brush and nothing remarkable there. I'd rather not just throw parts at it.....any help? Thoughts?

Much appreciated