Bseed Wall Switch with T34 Chip: Flashing Issues and Serial Connection Timeout

Hi, I've bought two Bseed wall switches, with T34 chip, and it seems impossible to flash it. I have the RX/TX soldered and connected to a USB-to-serial, and also VCC (3.3 V) and GND. But when I try to flash it, the result is the same: timeout trying to connect to the device.

- I've also tried connecting VCC and GND to different USB-to-serial (but GND was also connected to the USB-to-serial used for TX and RX) with the same timeout error.
- Tried disconnecting and reconnecting VCC during the flash process or changing RX and TX connection, but no luck.

*The device seems to not have access to the CEN pin without extracting the T34 chip from the PCB.

Has someone experienced the same problem with this device version and found a solution? Was bought on AliExpress:
BSEED WIFI Wall Light Switches Glass Panel Parts White Smart Touch Switches Function Parts EU Sockets Power Outlet Parts
But the device is not the same model from the AliExpress photo which has the explanation on how to flash in this forum:Link

Thanks in advance.

Are you powering the T34 with the 3.3V from an USB to serial adapter? It might be simply not enough to fully power the switch. Do you have a more powerful power supply?
Then, no offense, double check to connect RX to TX and vice versa.

Then check the length of the serial connection and try to keep it as short as possible.
If not already done, try lowering and even increasing the speed to see if this changes anything.