i'm having the same problem. it is really wrecking my head!
i only got my SB-600 a week ago and bought brand new batteries for it. it worked a few times on the first day i had it and then intermittently. but now it won't work at all. the screen lights up as normal, but will not test flash. will not flash on hot shoe. will not flash remotely. it would beep 8 times remotely which i thought initially was a setting issue like perhaps aperture etc. but the fact it won't test flash worries me. i've reset my csm settings and also i've reset the flash unit. double checked settings.....
i've read so much on the internet .. but i'm not getting anywhere. i'm going to get a new set of batteries .... but hope i won't have to send the unit back, cos i bought it online from a shop in HK!
