Have I bricked my esp32

Try it without specifying a baud rate. I think ESPtool.py will try and find one that works.
For example this batch file to read the chip info:

:: Read ESP8288 or ESP32 chip info
set /p pport=Enter a Com port 
echo %pport%
pause
esptool.py --port %pport% --no-stub chip_id
esptool.py --port %pport% --no-stub read_mac
esptool.py --port %pport% --no-stub flash_id
pause