Corroded flash contacts
I'm usually pretty diligent about removing batteries from my flash units, but this time I forgot and I had a AAA leak inside an unused flash unit.
I cleaned the contacts with sand paper, white vinegar, and rubbing alcohol, but I still cannot get the flash to power up when I put fresh batteries. There's still some corrosion on the terminals which are at the back of the battery box in an area hard to reach even with a cotton swab.
I read about the dangers of opening up a flash and being zapped by the electronics, so I'm not sure what steps to take next...other than the steps that take me to the trash bin :P
If it helps, the flash in question is one of those tiny Sunpak PF20XDs.