Although 'System Software Missing' is a type of 'bricking', it's quite different from a device which cannot start because of a corrupt file unable to load during the boot-cycle. As i explained in Post #320 (if we discount a hardware problem) the message usually means the data is region 14 is lacking.

So to summarize the problem: You were able to flash cure fw and can then access MSM but are unable to read or format the internal memory. My conclusion: Region 14 is able to be written with new data - usually the 'System Software Missing' message would then not appear and the device would operate normally once original firmware was flashed, or it'd simply stall on the Garmin logo screen with no message at all if cure fw was flashed. Perhaps this device has had its memory corrupted, maybe even by a virus. Because you don't know its history we just need to make some assumptions ongoing.

My suggestion is to try a low-level format with cure firmware loaded. I doubt you can damage the device more but hereon it's all at your own risk. Download the tool from the link behind the spoiler below and see if it can re-format the internal memory to FAT32. If it ends up showing in Disk Management as 'RAW' after a LLF then use [Only registered and activated users can see links. ] to properly format it to FAT32.
Spoiler:
http://hddguru.com/software/HDD-LLF-Low-Level-Format-Tool/

If LLF Tool cannot wipe the drive and at least revert it to RAW then the only other possibility is that physical damage has been suffered which cannot be fixed using software solutions.