Rebuilt TCM, still not working?

Hello!
I received a remanufactured TCM from Upfix for an 08 Mazda 3. After installing, I am getting a different error code and the transmission is stuck in limp mode. This is not the same problem I had before. I have done everything I can think of, and I believe the remanufactured TCM may be bad.

Here is the long version:
Originally the car would intermittently throw code p0791 and p0720 and unexpectedly downshift, exclusively on hot days. All three sensors were changed, transmission fluid and filter replaced mutiple times. But the problem persisted. Which led me to believe it is a TCM issue.

Upon installing the new TCM from Upfix, the car shifts hard from 1-2, 2-3, and as soon as 4th is required, it throws p0715, CL and transmission light comes on. 
I did all the steps advised by Upfix in the documentation that came with the rebuilt TCM including cleaning the connection with electrical contact cleaner, shorting the positive and negative battery leads for over an hour (battery out, of course!), and cleared the code mutiple times. As soon as it wants to go to 4th, the lights come back on it, code reader shows p0715, and it stays in 3rd.

Out of an abundance of caution I replace the input speed sensor (again) as that is what p0715 says in the issue. I back-probed the sensor (it is outputting voltage), checked continuity in the hardness to/from the TCM from/to the sensor (all good), and attempted to find a short or lose connection by wriggling the harness all around (nothing). 

Upon installing the old TCM back in the car, the limp-mode and p0715 are gone, shifting feels normal and I can get back into 4th, but I suspect it will throw the old codes again if I drive it long enough. 
I put both TCMs in the car so I could swap them easily, and going back the the new one again threw p0715 immediately. Back to the old one, no issues.

So, how can I proceed? I don't know what else to check, besides believing the remanufactured TCM I received is also bad. Otherwise, why would 2 different TCMs be throwing different codes, at different times, and replacing the sensor the "good" TCM is telling me to does not solve anything? 

Thank you,
Eric