Transmission Issues in 2021

Title: Transmission Issues in 2021

Hey all,

I've been experiencing transmission issues similar to those that others have had in the past, and am hoping for some help to understand how to diagnose and fix these problems. I've had the same issue three times in a month now:

1. I drive the car for a while with no issues (the first time I had been driving the car for about 3 hours, the second time I had only driven it for about 30 minutes)
2. Park the car and turn it off for a little bit (the first time this was only a few minutes as I filled up for gas. The second time the car was off for ~2 hours)
3. When I go to restart the car I get the "Christmas Tree of death", reverse and manual mode are not available, and only 2nd, 4th, and 6th gears work. The first time this happened the car actually got stuck in reverse for a bit before it finally went into neutral, but then couldn't go back to reverse or into 1st/3rd/5th.
4. No amount of key on/key off/reboots changes anything. If I pull the negative battery terminal AND let the car sit about 30 minutes, it will suddenly fire up just fine. All the warning lights go off except the CEL, all gears and modes are available, and the car shifts just fine. After driving for some amount of time, the CEL also clears itself.
5. The third incident occurred while driving this morning. On the freeway with the cruise control engaged and car in auto mode, the transmission light briefly flashes, CEL illuminates, I get a bunch of warnings, but the car continues to shift fine in auto mode. Once I parked and turned it off, it now has all the same problems as in #3 when I try to restart it.

After the first occurrence, I took the car to the dealer and they could find nothing wrong. They double-checked the software was up-to-date (I even provided the number of the SW patch below) and confirmed there was nothing available. They then quoted me $9,000 to replace the transmission, so I took the car back and decided I would have to solve this myself.

To start, I've read all of these threads:

Transmission Failure
Transmission Failure Poll
Heads Up On a TRny Issue
Inconsistent Problems: “The Christmas Tree of Death”.

The problem is that the majority of the problems people had occurred early on, and dealers either solved the problem with a software patch which predates the build date of my car (I have a 2016) or they replaced the transmission. My car is out of warranty so a trans replacement "just in case" is not in the cards.

From what I can gather, these are the possible sources of the problem. Is this list complete and in which order should I troubleshoot this?

• Clean/brush battery terminals and add dielectric grease - already tried this after the first incident, didn't solve the problem
• New battery - I tested the battery at Autozone, they claim that it's totally fine, not even marginal on startup
• Get the software patch that worked for others (CFC8TDW.01-00-UF14M080) - I gave this number to the dealer and they claimed everything is up to date
• Check/refill "Robot mechanism" (shift actuator?) fluid level
• Replace shift actuator pressure sensors with this part: Pressure sensor - Alfa Romeo TCT - SequParts
• Replace voltage regulator for shift actuator
• Replace hydraulic actuator p/n #68303710AA
• Replace transmission

Also, is anyone aware of an Alfa tech or indie shop somewhere in the US who actually has experience troubleshooting and solving these issues? The tech at the local dealer had seen this problem many times on Fiat 500Ls, but said that they just R&R the transmission every time, so he didn't have any idea how to diagnose the root cause.

Any help would be appreciated, I don't feel like I can trust my new car enough to drive it anywhere until this gets sorted out.