With no chime, I suspect capacitor leakage. You should get some sort of sound with a dead battery, either a chime or a crash. I run my IIci's with no batteries for fear of the dreaded explosion.

If you have ever had a leaky battery in a IIci, acid will go through a hole in the bottom of the plastic battery holder onto the logic board and eat a trace that goes to the ROM chips. This can only be found by unsoldering and removing the battery holder and inspecting the traces.