Seeking good method to locate short on buried AC power cable
Cheapest and easiest: Put a load (e.g., incandescent light bulb) on the short circuit (A to neutral).  Then follow the cable with a non-contact AC current detector.  The detector will stop beeping where the (first) short circuit is, since that is where the current is able to loop back in the cable.

If the voltage across the short is really that low, you may have to use a very low resistance load to get enough current to detect above ground (assuming the cable was properly buried).