No. The 3 screws on the underside are not sealed so that pressure equalization can take place. This is technically necessary for an accurate measurement result.
Air humidity also gets inside with the air. Especially during rapid cooling, this can condense on the display. This is a normal behavior and does not affect the function. With rising temperatures, the display usually dries by itself. If this is not sufficient, place the Blumat Digital in a warm and dry environment. If you unscrew the Blumat Digital, drying will be accelerated.
Water may have penetrated through the 3 screws on the underside. Unscrew the Blumat Digital, remove the battery and wait until everything is dry again. Then close the Blumat Digital again and check the function.