I have made it so: Zuert the two screws solved besides the batteries and then deducted the slide cover with a little pressure to the rear. Then levered with a small screwdriver on unterren end in the two slots the top half upwards and then worked on both sides up until I came to the contacts. Short drübergewischt and clicked everything back together.
It's strange where this fluid comes in several at the same place. My next TV will be in any case thus not be Sony.