Will not charge after battery replacement! Where to start?

Greetings,

Purchased a replacement battery here and tools and used the excellent guide to replace the battery in my 3GS. All went well, and it initially fired up and ran fine, but it became apparent that the battery was not charging. I just re-skinned it and very carefully reassembled it, no change. I get the lightning bolt and empty battery icon with a sliver of red, and it has not moved or woken up past that after a half-hour of charging over USB off my laptop.

I tried rebooting by depressing both buttons for 8 seconds, and it does shut down and then reset momentarily afterwards, but returns to dark screen w the same display - empty battery and lightning bolt.

I purchased the stuff in June of this year and I think I saw posts referring to a bad batch of batteries. Is that a possibility? I do believe I have it back together correctly and the dock connector and its contacts both look fine.

Thanks in advance for an approach to troubleshooting this.