In answer to question.
I deleted the library called "HCARDU0023_LiquidCrystal_I2C_V2_1" and just to be sure I recompiled the sketch form the first post at the top of this topic. the compile failed with a "no such library" message.
I then redownloaded the zipped file from the first post at the top, extracted the zipped files into the arduino libraries folder and recompiled and uploaded the sketch from this first post. It compiled and loaded ok; but only the "H" appeared on the top line and only the "*" appeared on the bottom line of the LCD.
![Smile :)](./images/smilies/icon_e_smile.gif)
Have you any other ideas? or should I ask for an LCD replacement?