Hello and welcome to the forums 🙂
Can you provide any more information as to what series of events leads the site to crash? If you haven’t already, I recommend taking a look at our ‘New User Primer: Event Tickets & Event Tickets Plus‘ article. Also, I see you checked ‘Yes’ to reverting back to the default WP theme and deactivating all other plugins than ours, but can you please confirm this?
Have you tried deactivating and deleting both Event Tickets and Event Tickets Plus, then reinstalling them manually? Please make sure you have the default WP theme active and all other plugins deactivated when attempting this. Also, make sure to do a backup though this process shouldn’t jeopardize your saved event data.
Thank you for choosing Event Tickets Plus and have a wonderful day.
Cheers!