Hello everybody ! And best wishes for 2024 !
I had tyhe same issue and wwas very disappointed to "destroy" my new R4 Wifi when trying the same update as you.
I couldn't connect it anymore because it was enlessly disconnecting/reconnecting USB, and identified falsely as WiFiduino V2...
Rapid pushes on reset button could not force recovery mode...
I was totally stuck 
By reading many many messages from a wide variety of sources, I finally got A SOLUTION !
- (1) download an archive with the firmware and utilities [Firmware v 0.3.0] same files exist for OSX and Linux. Unpacked the archive and navigated to the folder with a CLI (keep it open for later !)
- (2) disconnect the board
- (3) shorten with a male-male wire two of the "six pin" connector near the reset button (the one circles and the neighbour one iin the direction of the Arduino logo).
- (4) reconnected the board. The "bridge-wire" forces a special mode where you can flash the firmware and is signalled by an orange blinking LED.
- (5) used the CLI to lauch the batch "update.bat" to flash the R4.
- (6) disconnected board (power off)
- (7) taking the "bridge-wire" away
- (8) reconnect board
It worked ! It was such a relief 
I was just a bit disappointed not to see the welcoming heart animation (I DLed it later)
All my apologies for my hesitating english, and my unexperienced vocabulary. I'm new to Arduino's ...
Hope this helps !
(Note : when posted, I noticed that the link for the firmware isn't usable, so, URL is
https://github.com/arduino/uno-r4-wifi-usb-bridge/releases/latest/download/unor4wifi-update-windows.zip