I recognize the symptoms as to what has happened to me last night, while I resumed a game of Risk. The phone just switched off, I tried to reboot, after which it gave me a multi boot menu and than wouldn't go any further. Nothing after that. Just out of the blue. Nothing installed, uninstalled, no tweaks, nothing.
Concerning not being able to get flasher running properly: What OS are you using to run the flasher? There are numerous reports of Win7 64 bits being problematic, but I am on Linux so I can not confirm that first hand. I ended up reflashing the kernel only(!), and was set again.