I had a similar type of issue and chrome console pointed toward checkout.min.js
that is core file of woocommerce which is responsible for all checkout tasks but issue was not in that file it is somewhere else and we have to find that
what you can do about that is deactivate all the plugins except woocommerce plugin and then try if it works fine then you are good to go for next step and that is activating each plugin and testing after that
This method could take a long time if you have many plugins but you can group plugins like first 5 and deactivate them first and try if everything runs fine then next 5 and so on
you will find a culprit plugin. which may have hacking code or some events are calling on checkout
In my case, there was a plugin called as Akismet3 which was full of hacking code