[CLIENT] Black screen when opening after client closed due to disconnection error

I've linked a prior bug report from another user to reuse their image, as my client looks exactly the same as it does in that user's post.

I've had the League client open all night, and about two hours ago it closed due to a connection issue (the modal that suddenly appears telling you there is a connection issue then counts down to 0 before you can forcibly close the client, which I did).

Now the client is black-screened whenever I try to open it. This is only on NA. I can login to my Japanese and PBE accounts just fine.

I've tried terminating all League and Riot processes from Task Manager.

I also tried reinstalling League, which at least allowed me to get to a login screen (the old login screen; it seemed to bypass the new Riot Client). However, when logging in, nothing seemed to happen (the login loading indicator just spinned for about five minutes).

Also noting that whenever I close the black-screened client, it asks me if I want to exit (Y/N) like the old League client rather than asking me if I want to exit or sign out.

Edit: After letting the client sit for some time, this error appears in the middle of the client: https://i.imgur.com/8t3z7O0.png