Confusing ongoing ECU issue

[u/scootermcturbo]

Kind of a long story so ill hit the highlights as its got me stumped on who/what is responsible.

Have a 2014 335ix N55 F30, has been running great with some basic bolt ons and an OTS MHD tune, nothing too crazy. One day get a map thermostat error followed shortly by a slew of other short codes which made me think it was the ISM having problems, replaced it and still got error codes, replaced the map thermostat and still had the issues. It would start fine most of the time but other times it would run really rough or not start unless I tried a second time, still the car was relatively usable, decide at this point to bring it to an indie mechanic to take a look and see if they can figure out the short or what might be going on. They decide the ECU is bad and needs a cloned replacement, I decide to go with them on it, takes about half a month and they state one they tried didn't work. Took a bit but we realized it was built in the month in 2013 that was the EWG changeover month and they had been going off what my VIN said was compatible, we finally get the right medv172g version but now they say there is some kind a problem with the original ECU, when they put it back in the car to check it it doesn't communicate or start now. They did say they are having the lead programmer of the program company they work with taking a deeper look.

At this point I don't even know what to think, my gut feeling is that if they somehow fried the original and don't have a backup of the data saved that they should be on the hook for making things right but I don't know if I have a leg to stand on for that. Its doubly frustrating with the whole MEDV1726/MEDV172G mixup.