@Asprin624
If the device was otherwise completely healthy but the DS's file system rgn83 (a garmin region is kind of like a partition) did have bad blocks then running chkdsk /f will not fix them them because the /f option only looks for errors in the file system data. Using the /f option, chkdsk isn't a physical repair tool. It collects orphaned files and fragments and isolates them but afaik it won't isolate the bad blocks or replace them from an invisible reserve of blocks called a 'provisioned area' which is invisible in normal use. I think that latter function is done by /r only, not /f. Blocks of solid state memory can go bad but not like in a hard drive, although gates wear out and memory pages or blocks can fail. The drive firmware/memory controller if working detects these and uses reserve memory pages/blocks instead from the memory set aside provided it hasn't already been depleted (it's limited) and it also controls writing or erasing of data. If a low level format is used successfully then it will do exactly that too but in the OP's case neither RMPrepUSB nor Low Level Format Tool completed successfully to wipe the file system visible memory so it would not prompt to replace blocks either, even if there were any. It's quite irrelevant regardless, because the problem seems to be that the DS's memory chip itself is kaput so bad blocks or corrupt files are not even relevant.