DRV8704: V5 pin short with GND

Part Number:DRV8704

described as the tittle 

the DRV8704 chip's V5 pin is shorted with GND and the chip is  heating 

the design is: STM32 chip generate pwm ,control the sleep pin-reset pin-CS pin at 3.3V level ,iso7241 is used to translate the 3.3v-level into 5V-level ,3.3v and 5v is isolated by iso7241.

the VM of DRV8704 is 24V.

when i measure the V5 pin ,it drop down to 0v from 5v. cut off power, i found that the V5 pin is short with GND.

i check the circuit and PCB design, no errors found.

so i confused.

if the V5 short with GND ,there maybe shorting pin.i do not find it.the status regsister set is default.

so, i want to ask ,in which case the V5 short with GND?