I have a Nikon SB-800 that I received in March of 2007. I have not used the flash more than two dozen times. I recently took it to Mexico with me and used it there about 6 times. Everything worked fine. I came back to the US and tried to use the flash a week later, only to see that a battery had leaked acid in the battery chamber. Now the flash will not fire. Everytime the shutter is released the flash led blinks for the three seconds stating that underexposure has occured, but the flash will not fire. It will not even test fire off the camera or on the camera. The flash unit sounds as though it charges, the ready led lights up, the CPU lens functions work, I reset all of the settings, and still nothing. Could the battery acid have ruined the flash unit itself? The acid has gotten onto the terminals, but there is clearly enough metal to have proper contact to the battery. I brushed the dried up acid out with an old tooth brush.
I know that the flash bulb is still good because several times changing the batteries, it would flash... the unit was not even in the on position at that time. I have tried three different sets of batteries... still nothing. I do not really have the money to have it repaired right now and I am hoping that it is just something that I am not setting correctly. I do not know much about flash and everything is borderline of being a foreign language to me.
If anyone can help me out or lead me in the right direction, I would greatly appreciate it. I am kind of desperate because it was a birthday present and is brand new and was expensive.