cuse845
As long as the computer "sees" the internal drive (with a single file !protected) you should be able to run the
Sony stock-fw-updater or the
PRS+Uninstaller.
Both to be executed on PC with Reader connected to USB, and should bring you back in a running condition.
The whole update-process should take not more then two (2) minutes, and nothing had to be copied onto the reader to perform the update.
Beside this general hints (I don't own a 600) I hope
kartu or
BenChen can help you out.