Dead transmission, no codes?

My old Mazda has served me well with 350,000 KM's but my curiosity has been piqued with this issue. The transmission did a hard downshift and lost reverse. No fluid leaks, no grinding or shudders. Shortly after this it went into limp mode and I managed to get it to a service station. On the way to the station the AT light fired up.
The service station tested it and found no codes the next day, checked the fluids and called me to come get it. I took it for a 20KM test drive and there issues had disappeared! No AT light, no CEL, no codes.

Later in the day I returned to actually take the vehicle home. Now it only had reverse and no forward gears. I left the vehicle were it was (not like I had much of a choice). A couple days later I was called to pick the vehicle up. No codes, no CEL. Drove it home (15KM) and was told nothing further could be done because there were no further codes.

Next day, no forward or reverse but plenty of neutral. Now, no forward or reverse or neutral. I can move the shifter (lights change from RDNM1/M2) but now is in park and cannot be moved. No codes, no leaks, no CEL. Just thought I would share this (bizarre event, at least to me) situation with the forum.
 
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2020 CX-5 AWD
You might want to try disconnecting the battery overnight and see if that changes anything, even if only for a short time.
 
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South Carolina
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12 MZ5 13 CX-5
Your TCM is dying, it's kinda a known issue. There is a guy on the MZ5 facebook group that rebuilds them for about a third of what the dealership charges. I can't remember his name as I quit FB a couple of months ago, but if you search you can find him.
 
Your TCM is dying, it's kinda a known issue. There is a guy on the MZ5 facebook group that rebuilds them for about a third of what the dealership charges. I can't remember his name as I quit FB a couple of months ago, but if you search you can find him.
Thanks!
 
Gave that a try initially. I am doing it again and will check it tomorrow.
Cheers!
Pulled the battery and reset the TCM.
Still stuck in park, shifter linkage is functional.
Cleaned power/data connectors and moved the TCM to the firewall.