Posting this as I have been trying to fix this for a number of days and could find no helpful solutions online.

For a few days my tablet has been taking a long time to reboot and wifi wouldn't turn on - would get stuck on "Turning On". Factory reset didn't help.

Noticed after reset that the notification for my sd card said it was safe to remove. Usually it would say that one has been inserted. Removed the sd card and problem gone - fast restarts and wifi connects.

I remembered that I had moved an app to the sd card to free up space. Obviously this had caused an issue.

Hope this can help someone in the future.