Delete phase? There is not normally a separate delete phase in nanova firmware loading. Most of the programming methods have you a) attach to nanovna in dfu update mode, b) Select and outload the new firmware file, and c) restart the nanovna in normal mode with new firmware. The programming software does do a bulk flash erase as the first part of the update process.
It is very hard to truly brick a nanovna.
Which software are you using to update the firmware? Are you able to get that software to connect to nanovna in dfu update mode?
