Need help - problem with upload code XIAO ESP32 3C

Hello, I use for a couple of month the XIAO ESP32 C3 - Board. Everything works fine. Uploading was no Problem! But then, from one minute to another, the IDE tells me:

A fatal error occurred: No serial data received

I changed the cable, I read the troubleshootinh from website, I press the boot-button, reset-button, booth, when connecting the board to the PC: the problem remain.
I checked other solution-suggestions. Boudrate and so on: nothing.

Thats the error message:

Der Sketch verwendet 227092 Bytes (17%) des Programmspeicherplatzes. Das Maximum sind 1310720 Bytes.
Globale Variablen verwenden 13524 Bytes (4%) des dynamischen Speichers, 314156 Bytes für lokale Variablen verbleiben. Das Maximum sind 327680 Bytes.
esptool.py v4.5.1
Serial port COM6
Connecting…
Chip is ESP32-C3 (revision v0.4)
Features: WiFi, BLE
Crystal is 40MHz
MAC: d4:f9:8d:04:00:e8
Uploading stub…
Running stub…
Stub running…
Changing baud rate to 921600
A fatal error occurred: No serial data received.
Fehlgeschlagenes Hochladen: Hochladefehler: exit status 2

I hope, there is anybody, who can help. What should I do?

Thanks.

Oh, the way to enter the boot mode is:

  1. connect the board to the PC
  2. keep press the boot botton and click the reset botton and then you will hear a ringtone and then release
  3. try again
    Do you mean you do that?