Sounds like corrupted mmc or firmware (not the device firmware - internal hardware firmware like gsm wifi controllers etc), are you capable of removing the battery (that would reset the hardware and load firmwares on boot)? If not a reflash might help as the device hardware gets reset during first boot after a flash. For mmc I have no clue what is available as I only did that with my n900... but checking the filesystem for errors and bad blocks would be my first thing to do.