If the chip sees A0 = High and we have
A0 = High
A1 = High
A2 = Low
A3 = Low
Truth Table says that Y3 Pin 4 = Low
Using DVM
Pin Voltage (V)
1 Y0 5.17
2 Y1 5.17
3 Y2 5.17
4 Y3 0.0027
So the chip is working! Just need to figure out why A0 is not Low.