Liftmaster garage door opener problem. my liftmaster garage door opener won't operate down with

Question

my liftmaster garage door opener won't operate down with the remote nor the wall switch. i have to hold the wall switch continuously to make the garage door go down and close. if i release the wall switch the door travels in the up position and the lights flash for about five seconds. i checked the safety sensors and the lights are both on ( sending & receiving). i thought that maybe my wiring to the safety switches may have had a short so i disconnected them from the connection @ the opener hoping this would narrow my search for the problem, but this did not work. same results. my area was in hurricane Ike and i had flooding in my garage. the sensors got covered with water. do you think they are faulty even though the indicator lights are working and i should replace them? i'm clueless at this time since i have checked the up and down travel limit ajustment settings also. what do you think i should do next?