Whats happens if bike is Fully submerged in water?

This happened to my duke 200 where it submerged in water during the floods that hit my city back December 2015 and the bike was only 6 months old at that time and it fully submerged. First i thought that the flood water might cause damage to the engine and battery but i was surprised. Duke is inside the water. Nothing happened to the bike, And i heard that the engine should not be started because it may cause the engine to fail and thereby it may void the insurance and warranty, so i did not ignite the engine after it was brought out of water.(It stayed submerged for 4 days) I loaded the bike in a truck and reached the nearby KTM service center and the bike was serviced. I heard that other brand bikes had few issues in their engines, batteries because of fill up of water. Luckily my bike had a usual service which will cost around Rs 3,500. Usually they will replace the engine oil, Oil filter, air filter, brake pads. The same was done on this service als...