u/sockpuppets

I have a relative that trusts their electrician. I've seen all his work and it looks well done. Then this just happened. It's the transfer switch for a generator. It looks to me like that cable took a massive amount of current and could have electrocuted someone touching the panel. They said it was hot to the touch and smelled like baking soda. I assume it's a ground line but people here would know better than me.

Is this a major failure and a bad install? I am concerned for their well being but they've called the same company that installed it to repair it.