I have a Uno R3 (label says Made in Italy) and otherwise looks like a Arduino original.
it will not put any output on A4 (SDA) or the dedicated SDA pin when using I2C to connect a LCD.
The expected clock signal on A5 (SCL) looks ok on my scope. But A4 SDA pin is pulled LOW and even a 4.7K resistor will not pull it up
The same github test code and LCD with same I2C serial board work ok on other Uno's!
Is there a solution apart from a new Uno?