Failure prediction: applying 21V (over voltage) to logic level translator

[davegravy]

I have the TXU0204RUTR between my SBC's UART interface and a cellular module's interface. Let me know if schematic is helpful here but it's a pretty standard connection between two UART interfaces.

Due to clumsy probing I think I accidently shorted 21V to one or more of the B1Y, B2Y, B3 or B4 which is the SBC side of the translator. Aside from destroying the SBC's UART interface and the TXU204 I'm wondering where else to expect damage.

I replaced the SBC and the TXU204 but either I have solder issues under the translator or the translator did not protect the cellular module and it's interface is also toast. I've tried resoldering the TXU204 a couple times (the UQFN pin pitch is extremely fine and easy to botch soldering IME) but can't get communication back. I could try swapping the module but it's very expensive and difficult to desolder so it would be helpful to know the likelihood that it's damaged. I have no access to the signals on the PCB to test, unless I scrape off / expose track copper.

[PGPG]

In my opinion there is very, very little chance this IC (with absolute maximum supply 6.5V) to protect anything against 21V.
If it were digital signal insulator then 21V from one side would probably not go to the other, but only probably as insulation is very thin and not protected against practically exploding half of circuit.