I struggled to get mine going too... Almost gave up.
My problem turned out to be the contrast setting.
The fact that you see something on the display as it powers down suggests you have it connected okay (enough).
Arrange to vary the contrast setting during init. Value can range from 0 to 127 (always OR'd with 0x80 before sending).
No need to try all values, just walk through the range.
Mine now works with many different libraries.
Good luck!