My sympathies. I am also recovering from a recent camera demise resulting from excess humidity in the case. As in about an ounce in excess. Fortunately, it occurred on the second to last dive on our trip. Noticed early in the dive that there was fogging on the LCD viewing window. Got worse during the dive. Knew it was a leak, but could not abort short of an emergency declaration. Camera functioned through the whole dive until I turned it off at the end. On the boat between dives, the camera would not go on; opened the caseand saw the water; took the batteries out.
Back on shore, a closer look revealed corrosion already on the battery terminals and on the contacts in the camera. Rinsed batteries and battery compartment in fresh water back in my room. Re-charged the batteries were OK. Camera dried and it still didn't work.
Back home, I examined everything carefully again and found another battery I did not know existed. It's a watch battery that supports retention of information in the camera memory. I don't know if cameras can function without this battery, as I have not been able to test things in an intact camera yet. I have an A570is and this battery sits on its edge in a slot near the AA batteries and memory card under a little plastic tab that has the battery ID number on it. Pull this tab up and the battery will come out, sitting in its holder.
I replaced that battery ($5 from Radio Shack), put in charged AAs and the camera still didn't work.
I then rinsed the whole camera in isopropyl (rubbing) alcohol, undiluted (which is already about 70%). A friend subsequently said it should have been about 10-15%. Who knows? The camera dried overnight and still didn't work. Moreover, now I saw blue corrosion which was clearly copper based, rather than iron, down around some of the AA battery contacts. That did it. I ordered a new camera.
Yours is probably dead, too. But, you might try the diluted isopropyl alcohol rinse, if all else fails. One thing I regret not doing was rinsing my camera with absolute (100%) ethanol. I have access to this, and should have done it (and probably preceded by a thorough freshwater rinse), as any water moisture would be washed away by the ethanol which would itself evaporate very quickly. Still probably would not have been adequate. I strongly suspect that fine wires inside were already interrupted by the corrosion that occurred during the 3+ hr exposure to salt before I got a chance to make a freshwater rinse.
LESSON LEARNED--I have learned the hard way to check the o-ring after each opening of the case.
My attitude had been that if it isn't broken, don't fix it. Yes, I did a thorough check and silicon lubrication before the first use. And, I did a thorough rinse after every dive. I should have been particularly careful when we dove in a circumstance of 1 ft visibility surrounded by milky water filled with very fine particulates. Belated inspection of the case o-ring revealed a lot!! of fine particulates embedded in the silicone grease on the o-ring and case. None of this stuff would wash off. It had to be rubbed off with a clean cloth or my fingers. It could be felt with the fingers as mild resistance against the o-ring (such as would occur with superfine sandpaper), but was more or less invisible, until accumulated in one spot.
So, I will be much more careful in the future. This was in Bonaire, incidently. The wind had shifted, allowing substantial swells from the northwest, between Klein Bonaire and Bonaire, to break as waves on the western shore. Shore diving was the pits for a day, and it took an additional day for everything to settle back to near normal. The only place of relatively decent vis. was the southeast corner of Klein Bonaire.
broken since it won't even turn on anymore.
I have a feeling that the several times it worked afterwards were just "hiccups" in the road to the inevitable. 
oh well.
