2005 Dodge Ram 1500 hemi 4x4. "clunk" then no trany movement.

Now it has no movement. It still shifts easily between all gears, just nothing….no movement. I did drop the pan and change both filters along with adding mopar atf4. No major shavings in the pan. The only code is PO700. We had no signs of any transmission problems up till that point, no slipping or anything. Transmission control module is the code referenced above. I hear it is rare for those to go out. I can have it towed and looked at, but before that I am trying one more swing from you guys. I can easily take the TCM out. Does a normal auto repair place have the ability to test it? Or do I have to take that to a transmission place. Once again total loss of movement, but still shifts smoothly, just nothing! Side notes: no check engine light was on. I just scanned for codes and the Po700 popped. Also the truck sat a couple of days before I did the transmission oil/filter change. I tried to start the truck-nothing. The battery was shot, alternator still good. So maybe the battery being almost done had something electrically (low to no power) that could have triggered something…or just coincidence?!