re-flashing it is easy, just do it using cheap PL2303HX usb ttl adapter ($5) for Cortex firmware.
https://github.com/keirf/FlashFloppy...doc/Install.md
once set up with the things needed, the Gotek can be re-flashed in about 10 seconds.
I suspect flashing won't work because you've blown it up.
Regardless, the Gotek will work without the display so if it is doing nothing with a pre-configured USB drive then your Gotek is toasted.
So buy another and next time be more careful with it.
Better to buy cheap Chinese PC version ($10) and flash it yourself rather than bend over and take it up the rear by buying from vultures selling "Amiga Gotek". That way you might actually learn something too.....