All right. You went to a different NEMA14-50; and your old and new TMCs charge sans problems. If I'm not mistaken, that wipes out any chances that your problems are with the car, the TMC, or the adapter plugged into the TMC.
We're now talking about the house and your electrician. Um. Hate to say this, but this is the same electrician who checked his/her own work and blessed same.
So, no offense to anybody, but I'm pretty sure that your electrician has made a mistake. Or that some piece of equipment that he installed was faulty, or became faulty over time.
One way to double-check this and (possibly) getting him/her on your side would be to have some other Tesla try (and likely fail) to charge at your socket. If All Teslas In The Universe Work Fine, but not at That NEMA14-50, then it's the NEMA14-50. Or something backing it up, like the breakers or the wiring.
Now, as it happens, I'm a EE. I don't work on city power, much, but, being in the field, so to speak, and having some experience replacing $RANDOM sockets, light fixtures, fans, and whatnot, I'm relatively comfortable with disassembling things electrical and putting them back together again. I used to be a RADAR technician before becoming an engineer, so you'd better believe I've had all that safety, safety, safety stuff drilled into me like you wouldn't believe; 15 kV power is nothing to fool around with. So, when I work on breaker panels, I got one hand stuffed in my back pocket, I tend to hit the main cutoffs, given a chance, and I double-check that things are de-energized with a working voltmeter. 120 VAC isn't
that dangerous (if one isn't damp, that is). You get the idea.
So, if I were you, I'd be popping the main house breaker, taking off the front of the panel, and
very carefully checking the wiring, both visually and with an ohmmeter. Ground swapped for neutral; a hot swapped for any of the other two wires; thorough tugging on various wires at both the socket and breaker end, possibly removing the breaker from the panel (they snap out) and, with an ohmmeter, verifying that both legs of the duplex breaker have continuity when they're supposed to and no continuity when they're not; pulling the socket out from its box, eyeballing the heck out of it and the wires around it, checking for continuity between wires and the contacts inside the socket, looking for cracks in the plastic, listening for rattles when it's shook; then putting everything back together again and trying to see if doing all that fixed anything. Looking for wires hitting things that they oughtn't, smoke/burn damage, etc., etc.
My old Chief Petty Officer said that (a) you'll find a lot on a visual inspection and (b) 90% of your problems will be in the wires. On the latter, he was dead right, but we're talking Naval Aircraft here, and they vibrate, lots, so wires break are very common. He was also dead right on the former as well.
Problems are, I'm not you, I'm not anywhere
near you, and I am very definitely not a licensed electrician, just a (somewhat) knowledgeable homeowner. And you've stated that you and electrical things in general aren't best friends. Without somebody knowledgeable showing you the ropes, I wouldn't recommend you chasing around the breaker box as your first learning experience. Any serious mistakes could be final mistakes.
So: In terms of whom to turn to. Um. So, back when I had my Tesla Wall Connector (TWC) installed, Tesla had been keeping a list of electrical contractors who, were, "approved" for installing TWCs. I mean,
any licensed electrician can install something like a TWC or NEMA14-50, this is more-or-less their bread and butter. I don't know how electricians got on that list. What I
do know is that the particular batch (well, two people, and their boss who set it up, who I never actually laid eyes on) did all the work properly and, more to the point, took
pictures of their work. I later got an email from
Tesla with a link to a location on a Tesla server somewhere where one could look at these pictures. Which were kind of interesting: Pictures of the breaker in the panel, wires exposed; pictures of the interior of the Gen 2 TWC, and how the wires were connected, and so forth. Not that I ever had any problems with that TWC since 2018 when it was installed. But, clearly, if some techie at Tesla got a complaint, said techie would have pictures to figure out What Went Wrong. And I'm guessing that this whole picture rigamarole was put in place because, well, there were probably electricians who
didn't get it right, and the process was put in place to help correct such failures. Nothing happens by accident.
(FWIW, a co-worker bought a M3 about 6 months after I had bought mine. He had a non-Tesla approved guy do the electrical work, and said guy flipped switches inside the Gen2 TWC, something that the manual (I actually
read manuals, cover to cover, but apparently that electrician didn't) says not to do. The electrician bugged out before checking to see that the TWC was working.. which it wasn't. It was fried. Luckily, Tesla was nice to my co-worker, drop-shipped him a new one, which he installed himself, having that level of expertise.)
I'm guessing that Tesla still keeps that list of Approved Contractors around. I'd suggest that you contact Tesla, get that list, find somebody on it who's local and
not the guy whose work we suspect, and have them come up to do an inspection.
What d'you know: Tesla has a
web page for this. Give it a shot?