iPhone cannot be restored (FDR failures)

I have a dead iPhone (no screen, 1 time seen apple logo). When connecting to iTunes/3UTools the phone seems to be in DFU-mode. HOME/Power-method doesn’t return it to normal. Flashing with iOS 13.5 using 3U tools/iTunes cannot complete. Mostly the error is a FDR-error. I’ve tried different a USB-cable and port. Any suggestions?

I’m a starter on repairing and this is my first ‘serious’ issue.