t520 Thinclient doesn't respond after upgrading to ThinPro 6.1.1 from HPDM 4.7 SP6

I'm currently working on upgrading our thinclient fleet from ThinPro 5.2 to ThinPro 6.1.1 using HPDM 4.7 SP6.  However, I'm not having a lot of luck with this process so far.  

So far, my steps and observations are as follows:

1. Upgrade the agent on the thinclients from 4.6.3670.20153 to 4.7.3670.26470
2. Push the ThinPro 6.1.1 image to the device.  This is the stock image downloaded from HP's FTP site - it isn't a captured image
3. The image deploys to the thinclient successfully but afterwards it no longer responds to the Device Manager.  The deploy task from the previous step is stuck "processing" and any future tasks are also stuck waiting/sending.

I can still ping the devices that are stuck in this state but if I run the "HPDMPortCheck" tool against one of the devices in this state I get "port 40001      FAILURE, 10061, No connection could be made because the target machine actively refused it." 

All devices get their HPDM address settings from DHCP option 202.  Any device that isn't on ThinPro 6.1.1 is finding the DM just fine.