Yes, your phone can die. The flash chip for example could fu*k up. You'd need to solder a new one then. This shouldn't happen but it's possible. Problems with GDFS are hard to fix too. In some cases you need software like SE Tool 3 Box which you need to buy first.

There is a thread here on TopSony explaining the difference between EROM and EROM FOTA. Sorry, but I'm too busy to look for it now.