You are probably okay, but I would like to know a few things to help allievate any worries you might have.
First, the fact that the main fuse blew is a good thing. The job of the main fuse is to protect the electrical system from this type of short or overload. I am assuming they put a charger on backwards and the main fusible link blew.
Let me know the following;

Was the fuse blown by the charger being put on backwards, i.e. reverse polarity?

Was the charger left on for a period of time and then the problem found?

Does the car seem OK now?

Has anyone put a multi meter on the battary to test it under load?

I will keep an eye on this post for your replay and get back ASAP.

Answered by DrCranknWrench (expert)
3,292 answers provided

That is great new to here! Lexus is good ay customer service and it sounds like the delership is well managed in customer satisfaction as well.
The main fuse did its job via self sacrifice to pretect the entire electrical system of the car. The only conern I had was the battery and since that is being replaced...this never happened. You actually got a newer battery!!!
I am glad it worked out well and your, "Baby" is being taken care of.
Take care and come back if you need anything in the future.

Dr. C

Answered by DrCranknWrench (expert)
3,292 answers provided