Now when I try to open and launch it, the green dot below it appears for a mere 2s and then disappears. I am now unable to launch it. Tried re-installing and it doesn’t work for me either.
Did you have any plugins installed? Those could be causing this issue. You can launch Glyphs without plugins by holding down the Option ⌥ and Shift ⇧ keys while launching Glyphs.