According to [1], you need to resolder only 1 resistor to tell BIOS that the soldered RAM is 16GB upgraded (in this case of upgrading the 8GB of soldered RAM to 16 on a Dell XPS13). Can it be assumed in a similar vein, that if E14 soldered RAM fails sometime, and you may only want to block it from usage and leave in the system board, so you may only need to fiddle with resoldering some resistors? Thou it currently seems like no, as I suppose the system board won't work at all without any working soldered RAM. So there need to be a way to inform the system board to not use soldered RAM and use inserted RAM.

[1] https://hackaday.com/2021/11/24/you-cant-upgrade-soldered-on...