How do you use the plastic cover/case that came with Arduino?
The cover was developed for Arduinos with on-board Ethernet with POE and similar cover has the Ethernet shield with POE. POE - power over Ethernet is 48 V, so it is better to not to touch a soldering point with this voltage.

The arduino.org boards were sold with this cover. Some of them had on-board esp8266 and soldering points leading to esp8266 sensitive pins. Again, better not to touch.

I used the cover to attach the Arduino to a DIN rail over a DIN rail clip.