Screen stuck after trying to load G-code

My screen is frozen. I can only operate the three little dots in the upper right hand corner. I was loading my first ever G- Code into the Black Box with a thumb drive.a very small file just two short words. It was taking a long time, like 45 minutes when it got to 100% it froze. If I turn it off and on it comes with this message every time and screen frozen.

Delete the files (click the bin icon & select ‘all’) that have been uploaded to the controller as it only has a certain capacity then try to load the file again.

None of those buttons work when this message is on the screen. I can’t use the bin.

Follow these instructions to delete the files …