Welcome to the forum!
Thanks for your description of the Shelly failure! Was it a neon tube which was switched off?
With some likelihood on of three diodes which rectify the three phase voltage at terminals VA, VB and VC got defective. This causes a three phase short with a lot of short circuit current…
Shelly pro 3EM avoids this failure mechanism: Supply for the device is fed by one terminal only (C); the other two terminals (A and B) are for measuring purposes only. This seems to be a big step for reliability!