LN-CB3S Module Pinout and Flashing Issues on Tuya Wall Switch – Any Documentation?

Any info on this module?

I could not find any information by googling "LN-CB3S."

It seems that this module has different pin labeling (and/or different pinouts) from CB3S module.

I connected A2 and A3 pins to TX and RX (and also tried to RX and TX) of my USB-to-serial (and also CEN to GND), but I cannot get it to enter flash mode.

This module is from a Tuya wall switch. Since I could not flash this module with any open-source firmware, I had to replace it with ESP-12F.

Any info would be appreciated.

Judging from module and pin names - LN882H.
Default RX/TX are for flashing (and app uart, if used), log should be at B9.

Backup can be taken with BK7231GUIFlashTool, chip enters flashing mode with A9 pulled down on boot