Nvidia received a number of report where users mentioned it is possible to break the power plug of the European adapter from its Shield tablets and Shield boxes (Android TV box). And that could result into an electric shock. 

Nvidia mentions in an explanation that the adapter (with metal connectors) can break under heavy circumstances and hence metal pins can get exposed. Thus far Nvidia received six reports from customers who were shocked that they got shocked.  Nvidia created a special help page where you can request a replacement plug. It only involves European Shield tablets and set top boxes that have been sold in-between July 2014 and May 2017. The product charger head has serial number SPA011AU5W2. 

-- Nvidia

NVIDIA has announced the voluntary recall of certain plug heads for SHIELD AC wall adapters designed for use in continental Europe, which the company will replace. The affected product shipped with SHIELD World Charger Kits, and European SHIELD tablets and European SHIELD TVs between July 2014 and May 2017. NVIDIA has determined that the two-prong European plug head – or “duck head” – may break, posing a risk of electrical shock. The recall is limited to the European plug head and does not affect any other NVIDIA products.

More info here.

NVIDIA Recalls European Plug Heads Sold with Shield Tablet and TV box