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Broken battery cover, how can i replace it with an new one ? What parts to disassemble ?

@noname_germany the battery compartment door is held in place by a pin (step 2 of the guide). You have to remove the back cover of your camera. there will be a small spring round the pin, watch the way it is installed. This will be important. Once the back removed, pull the pin (watch the spring) and that will free the door. Replacement doors can be costly, so check places like ebay.com and others Nikon COOLPIX S9500 LCD Screen Replacement will at least get you to the door.