After playing around with the cameras a bit more, it looked like firmware v2.1.5 on the repaired camera from 2021 couldn't recognize microSD card formats other than FAT32 while v3.0.0 can do exFAT. Windows didn't give me the option to format microSD cards with capacities higher than 32GB to FAT32, so I ended up using FAT32Format v1.01 to get a 128GB microSD card recognized. Still, 32GB would have been plenty of storage as 30-40 minutes of continuous recording (i.e., holding down the trigger) would only take up about 1GB of space on v2.1.5, and individual visible+IR images combined would take up about 2MB total. v3.0.0 on the functional camera produced videos that are significantly larger in size which made me think that there might be hardware and/or video-processing differences between the units. For starter, v3.0.0 camera finished booting a few seconds faster, had less motion blur on moving objects (could also be higher refresh rate on the screen), and overall was more responsive when taking/saving images. I'll probably tear down the v3.0.0 camera at some point later, but probably only after I decided on whether I should send the thing to ICI for firmware upgrade to v3.0.2. Per Infiray, the M600 firmware isn't compatible with the T-Cam, so that leaves ICI the sole source to get updates. I reached out to ICI to see if they would service/calibration check the camera, and it looked like they'll do it for $495 + ship + tax at minimum.
Videos for comparison:
Focus was adjusted to get the sharpest image in each case.
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After installing the Infiray IR Discovery Android app, the app could connect to the camera just fine after the phone connected to the camera's Wifi network. In terms of functionality the app could transfer images from the camera's microSD card over to the phone for analysis, but that seemed to be about it. I thought there would be video streaming functionality like the IR Discovery software on PC, but that was not supported I guess. On the bright side I realized that the PC software allows for recording of radiometric data up to 20FPS which is nice for when I want to do more serious analysis for work.