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@gabrielesvelto FYI, this seems to be a nonnegligible cause of death of Nintendo 3DS units. some units either exhibit strange behavior, corruption in text characters (which turn out to be single bitflips), or just straight up refuse to boot
it's possible to demonstrate these are indeed DRAM* errors by using the boot9strap jailbreak (with ntrboot if not installed beforehand), as these run from SoC-internal SRAM instead of DRAM. booting the OS then typically fails, and it can also be used as a point to run a memtest
problem is that replacing the DRAM chips is *very* difficult. not only would it require BGA rework (because it's so small they couldn't not solder it on the mobo), Nintendo also used epoxy 'underfill' to glue the DRAM chip stuck to the PCB to deter RAM probing attacks (as those were used against the DSi, the 3DS' predecessor), see the "white glue" here: https://giltesa.com/wp-content/uploads/2013/12/Nintendo_3DS_PCB-Top.jpg
*: DRAM is more often called FCRAM on the 3DS because that's the type of DRAM by fujitsu it uses
@gabrielesvelto though, when running such a memtest, in most cases the errors seem to have the same pattern throughout the entire DRAM.
this means it's probably a solderball crack under the DRAM or SoC, rather than actual semiconductor failure, though the latter is also sometimes observed