Jerry Hall

I have a 2008 Dodge ram 3500 6.7. The AC locked up and broke the belt. I was only a couple of miles from home so I went on in. It never got into the red. I replaced the AC compressor and when I went to start it up it wouldn't start. The starter engages, and after around 5 spins it disengages and re engages. NO START. it will start with starter fluid and runs fine. I do have an ETC light on. I have disconnected the terminals for 30 min, I have had the batteries tested and I have tried known good batteries and I have crossed the two positive terminals to rule out a bad cross wire???????