If you get a direct hit from a lightning bolt that melts your power post, the surge portion of your EMS likely needs to be replaced. That does not happen very often
You can verify the need to replace the surge board by the fact that the MOV's have split open ...
In normal use the MOV's are good for a couple hundred reasonably large hits. The unit may or may not disconnect depending on the duration of those hits. Do a large number of smaller hits also cause the MOV's to split? That depends ..... it certainly *can* work that way.
If you want to see a cracked in half MOV, pick up a surge suppressor outlet strip at a garage sale. You want the one that obviously has had a long and hard life. Spend a max of about 50 cents. Pop it open and there's about a 50/50 chance the MOV's are blown.