To shed some light in this more or less theoretical discussion it would be brilliant to get some more facts:
Is the device irreversible defective?
Does a red light glow in the innards (may be seen from the backside near the reset button)?
If true: Does the light blink or does it glow permanently?
If the light is visible: Does the reset button react?
Push the button for more than 5 seconds: The light should blink fast!
Push the button for more than 10 seconds: The light should blink faster!
After the reset procedure: Is the AP of the device visible in WLAN menu of your smartphone?
In the case, NO light is visible:
Ask your electrician to check the voltage between pin N and L of the Shelly EM!
How large is this voltage?
Could you show us a picture of the installation? Possibly with all the wiring visible?
Many thanks for your patience!