iPhone 4S does not get "Service" after battery replacement

I replace batteries in two iPhone 4S using the IFIXIT instructions. Both appeared to have had similar issues in that they could not get cellular service afterwards. One phone I was able to resolve using the date/time change method.

The other continues to be problematic. I have resat the connecters, verified the antenna is connected properly, replace the original battery, restored the phone. charged each battery to 100%, and turned in off and back on again like recommended in "The IT Crowd".

I notice that (besides no cellular service) the phone gets hot during charging on either battery. I don't get any overheat warnings or other functionality issues.

I know batting .500 isn't bad, but I am a bit of a perfectionist.

Thoughts? Solutions?