Firebeetle bricked?

Hi,

I'm afraid I've bricked my Firebeetle 2.
After a flash process was aborted with an error,
my ESP32 no longer boots:

ets_main.c 331 
ESP-ROM:esp32c6-20220919
Build:Sep 19 2022
rst:0x7 (TG0_WDT_HPSYS),boot:0x68 (SPI_FAST_FLASH_BOOT)
Saved PC:0x40018bea
SPIWP:0xee
mode:DIO, clock div:2
load:0x42150020,len:0x90fc0
load:0x40800000,len:0xd9c4
load:0x4080d9d0,len:0x1664
load:0x42000020,len:0x1491ac
Invalid image block, can't boot.

Now I can neither reflash via USB nor with UART.
I have tried both with esptool and with Arduino.

What can I do?