Hi everyone!
Thank you all so much for your replies, I really appreciate it!
Turns out I was missing a Permission Set in Salesforce that was causing the page not to load, so after reverting back to the unedited version I still had to add this Permission Set. But it seems odd as I never had the Permission Set in the first place and it was never an issue.
Oh well it’s resolved now so no worries.
Thanks again.
