LS-4P: How to flash with USB-Serial-Adapter?

What happend:

I tried to update WLED Firmware from Stock-Rom to 0.13.3.

First I tried with ESP8266 Version without success. Then I tried ESP01 Version with success but my device is bricked. I think, it should be ESP02-Version.

I opend the LS-4P and put my USB-UART-Adapter on it:

VCC to 3V3

GND to GND

TX to RDX

RDX to TX

Front Picture of the LS-4P Controller:

https://templates.blakadder.com/assets/device_images/athom_LS4P_1.webp

Then I tried to get the ESP into flash-mode with a wired bridge between RST and GND.

https://templates.blakadder.com/assets/device_images/athom_LS4P_2.webp

Tried "Easy ESP Flasher" with following error-log:

espcomm_send_command: sending command header

[22.10.2022] espcomm_send_command: sending command payload

[22.10.2022] serialport_receive_C0: 52 instead of C0

[22.10.2022] warning: espcomm_sync failed

[22.10.2022] error: espcomm_open failed

[22.10.2022] error: espcomm_upload_mem failed

[2022-10-22] STOPPED due to 2 errors! (try reset on the unit, then start a new flash attempt)

Any idea how to "re-flash" with correct binary?