I had the same thing happen to me twice already and both times the same thing solved it for me
I took my kindle out of the charger I took its case off and just left it bare.
I then left it face down on my nightstand and waited for a little less than 24 hours (i suggest waiting the full 24 hour time though just in case) and finally the kindle completed its restart sequence
I think this worked cause that the problem occurred right after you restarted so the kindle just needed to get some time to restart (i’m not sure if taking off the case and taking it out of the charger was necessary but u should still try it b/c thats how it worked for me)