If you are not getting a PG error than I am doubtful of a bad encoder. When you give it a run command does it attempt to move the spindle? Typically bad encoders will move the spindle a little then error out with PG. You can kinda check the encoder with a multimeter, manually set voltage range, connect to 0V pin and one of the PC (A,B, or C) slowly rotate the spindle, that is more than likely a 1024ppr encoder so the difference between a high and a low on one set is going to be extremely small. Logic analyzer or oscope is a more effective tool for testing, when a digital multimeter is used and on autorange the sampling is often to slow to catch the high/low signal change when the encoder is moved to fast.
Try unplugging the encoder and attempt to run it. (should get a PG error) If you dont get an error here, then there is something else blocking the spindle from attempting to run.
If the spindle will not move at all are you sure you have all the permissive met ?
Estop, ready ? and an analog speed input ? Or forward or reverse run and a digital speed input ?