I connected up Grove 16x2 LCD to my Uno R3 and hooked the power up to the 5V SCL and SCA to A5/A4. When the display powers up I get the top line with all the segments on and the bottom line all the segments off. No display output that I can see, Tried adding 4.7 pull ups to the SCL/SCA but still no joy.
Sorted it - poor soldering!!