I know you have a Just Add Sharks Blacknose cutter running Lasercut 5.3 & Leetro 6515 controller with PAD03 LCD and input panel.
I can tell from what you’ve written that you interface with your laser cutter, probably using USB drive and uploading files directly into the laser cutter and you’re trying to delete files using you key pad on the cutter.
You’ve loaded too many files into the memory and now the controller won’t function. Connect to the controller with the USB cable and access the controller via the Lasercut 5.3 software. Once you have a connection between your computer and the laser cutter, click on the DOWNLOAD button on the right side of the lasercut5.3 work area.
A dialogue box should open, a list of all files resident on the controller on your laser cutter should appear. You can either DEL (delete) a few by highlighting them, OR you can DEL ALL with a button on the pop-up dialogue. This should remedy your problem. Don’t use the Leetro 6515 controller for files storage.