Optiplex 3030 AIO - cannot install / upgrade Windows 10 anniversary ( 1607 )

Dear all,

here's a weird issue with an Optiplex 3030 AIO on a customer site...

The system was initially bought with Windows 7 Pro SP1 and back then in late 2015

updated to Windows 10 Pro. Everything was OK so far with this setup - no issues at all.

However - this specific 3030 AIO tries to apply the anniversary update (1607) as well - but fails.

When it's doing this from within windows itself it reboots automatically (as part of the update process)

and starts applying the update - but will hang there at 30% for days (started update at friday afternoon - met customer at monday... and the Optiplex 3030AIO still showed the spinning circles

at 30 percent.

We tried this 3 times within the last 8 weeks (and cleaned up SoftwareDistribution\ folder after each fail) with no success in installing the anniversary update. After a cold reboot - Windows 10 rolls back

to the previous version and keeps working fine until the Windows Update magic decides that it's time

for the automatic upgrade again...

When this happened for the 4th time (earlier this week) we removed this Optiplex 3030 AIO from

the customer site and thought it would be good to reinstall from scratch -  using the latest installation media (USB) offered by the most current media creation tool.

Problem - we cannot even do a clean install of the anniversary release - although DELL claims that

the Optiplex 3030 AIO is fully supported (see SLN297954 in DELL knowledge base).

When doing so it never finishes the (last) 'Finishing up' part in the stage where it shows the current status and each completed stage gets a green checkmark.

What we've done so far:

1. did ran the builtin diagnostics - but skipped the HDD part (smartctl from a linux live cd showed
   no errors) - no errors
2. tried a couple of known to work USB sticks with the anniversary installer - some even newly
   recreated using the latest media creation tool
3. we even tried an anniversary DVD iso

... all attempts failed with the same phenomena (never finishes the 'Finishing up' stage).

What we've also tried:

1. we ran the installation using the very first (august 2015) DVD iso of Windows 10
   ... wow, this works - but...
2. ... as soon as the very first Windows Update run tries to apply the anniversary update (1607)
   we're back at our problem (hangs at 30%)

This Optiplex 3030 AIO was part of a bigger order (including server) and we (the customer) is

still eligible for next business day onsite until somewhere in 2019.

Tried to open a ticket over here in germany - but the DELL support clerk refused to do anything because he insisted that this is a software issue and he cannot do anything for me (... offered me

payed software support and even suggested that we ask microsoft for support). There was no way

to convince him...

We're - however at a loss and hints are most welcome!

Thanks for (quite long, sorry) reading...