servo stopped working after rain

[pacantre]

r1150r 2004 abs 21kmiles
I rode for about 20 min in rain today. when I stopped I noticed that my servo is making a sound even though brake levers were not pressed. I believe it had something to do with rear brakes, because I pressed front lever - it made sound slightly different , when I pressed rear the sound got stronger. I also noticed my brake light was on.
I shut down the bike and started again. servo stopped working at all , even when I pressed brake levers and abs light started to blink fast - at 4mhz. rear brake light is still on.
I read that rear brake sensor sometimes might be an issues. what do you guys think ?
thanks