Bruce,
Most common problem with owner serviced VM1000 units is wiring problems upon reinstallation. Before ordering a new chip, I would recommend a complete check of your terminal connections, especially the power and ground connections both DPU side and ship side. If you have a serial connector type DPU, then this is a much less likely scenario.
You can also troubleshoot by reinstalling the known good chip to see if the DPU will boot.
In the 100s of NVRAM modules I have replaced for VMS DPU owners over the years, I have found 2 that were actually bad from the manufacturer. So the likelihood is small but possible to get a 'bad' chip.
Please let me know if I can assist further.
All the best,
Reggie
http://vmsupport.weebly.com/