Plugin Crashed

I have been using this plugin for few days and it worked great. I successfully imported 2000 product with no issue. Then yesterday I ran the import for customers (70,000) and orders.
The customers import process got completed in hours but since then I am not able to open the customers page or the plugin. It just keeps loading the page and then throws an error.

Also before the plugin got closed a few of the orders got imported. What I noticed that the order sequence was missing the order prefix “2” that I was using in shopify. Any way to import the orders in a way that the prefix part is included as well.