you could probably transplant the CPU from one system to another (this has already been done once by someone to make a US small n3DS before the official release but its no simple feat and probably well beyond the capabilities of 99.9% of people
what exactly happened to the system? as in most cases it would probably be easier to fix the console in question
If i understand well, theoretically could be possible transfer 3DS identity tranplante "CPU" and NAND chip to other mainboard (NAND CID is used for generetaing AES CTR)...