Allo MINI BOSS failure - How to troubleshoot

[Eric R]

I've had a Allo MINI BOSS DAC on a Rasberry PI Zero W since February.  It was plugged directly into an old Haffler amplifier.  The Pi Zero runs MOODE.  All was fine and then the connection to MOODE died.  It looked to me like the Pi had died.  The green light on the Mini Boss was still on.  I bought a new Pi Zero, moved the SD memory card over put the Mini Boss on top of it, and turned it on.   Green light on the Mini Boss but rasberry pi zero appears to be dead.  Took the Mini Boss back off the Pi and tried plugging the pi into my windows 10 laptop USB port.  Windows does not register that anything is plugged in.  I think the Mini Boss is killing the Rasberry Pi.

 

What could be wrong with the Mini Boss that it kills the Pi.  How can I tell?

 

Thanks in advance for helping?