Replacing the batteries is a simple operation that does not affect the warranty in any way.
The batteries used are 2 type C alkaline batteries - 1.5V LR14, a type that is easily found even in the supermarket.
Here are the steps to follow:
1. Turn the SOLO device upside down and unscrew the 4 screws using a Phillips screwdriver
2. Remove the cover. Between the two shells there is a rubber gasket that prevents water from entering, to separate them it is necessary to lever evenly from the 4 corners with a flat and rigid object, such as a flat-tip screwdriver.
3. Remove the batteries
4. Insert the new batteries, orienting the positive (+) and negative (-) ends as indicated on the labels affixed to the housing
5. Close the cover and fix the 4 screws on the back again.