Ender 3 Pro, Motherboard v4.2.7, Marlin 2.0.1 Firmware reset Upgrading motherboard to v4.2.7   How do I reset the firmware after making wrong mods?
You could download the firmware version directly from the vendor and choose the one that is supposed to be on the board when it was shipped to you.
Put the bin file on the SD card from your laptop/computer and reinsert the SD card in the printer and start the printer.