DRV8428E: locked out or damaged? chip does not reset on power cycle acts dead

I am attempting to drive the following bipolar stepper motor: https://www.omc-stepperonline.com/nema-17-bipolar-1-8deg-26ncm-36-8oz-in-0-4a-12v-42x42x34mm-4-wires-17hs13-0404s1?search=17hs13-0404s1

using the DRV8428E. in the following configuration:

1-VM=+12Vdc, 16-nSleep=+3.3Vdc, 11-DECAY/TOFF=GND,R1=10k,R2=3.3K,Vref=~.8188V.

Using the following truth table:

After several attempts of stepping the driver goes dark and no longer works. This is now the second chip that I have experienced this. resetting power does not rest the chip; it appears to be locked out or damaged. On the second chip I also tested prior to installing the motor with four led's to show the polarity of both bridges and this worked fine until the motor was connected then a repeat result of the first test. my co-worker has also now had 5 chips stop working in the same conditions using various vref values. Please advise on how to proceed.

Thanks in advance.