Hi,
Possible reasons fo a display glass not to work:
1) Display glasses are manufactured for a dedicated driving voltage.
So if the new one is designed for a higher voltage than applied, then it's possible to see no activated segments.
2) shifting the SEGment connections will just cause different segments to be activated, but they should be visible.
But shifting the COM connections may cause the segments not to be activated. Check proper COM connections to your display controller.
3) LCD glasses work by shifting the light's polarity angle, thus they need a polarizing filter. If this polarizing filter is missing you will se no activated segment.
I don't know how those filters are specified, but I assume for a test you could use one designed for a photo camera. Ask a photographer to get one for tests.
Test: use the filter and place it over your unconnected display. Rotate the filter with respect to the display glass. Look through the filter to the display glass. If the display does not change color (it should become 2x dark and 2x clear during one complete revolution), then there is no filter applied on the display.
* In this case connect the display, use any test pattern, place the filter on top of the display. Rotate the filter while you check for activated segments.
* If you see clear and dark while rotating, then a polarizing filter is already applied on the display. No need for an extra filter (photographer) for further tests.
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You may do some tests with DC by hand. Note: Permanent DC may cause damage to the display, but for a few seconds it should be no problem. Applying 5V, one at a SEG, the other to any COM, should activate a segment. Polarity does not matter.
Good luck.
Klaus