VHDTool - a must have.
This tool saved me lots of time. So I thought I point you to it:
https://code.msdn.microsoft.com/vhdtool
Among some other nice features, my favorite is repair
Repairs a broken Hyper-V snapshot chain where an administrator
has expanded the size of the root VHD. The base VHD will be
returned to its original size. THIS MAY CAUSE DATA LOSS if the
contents of the base VHD were changed after expansion.
Cheers
Robert