Problem with updating firmware ESP-12 (ESP8266) to ESP8266 AT Release v2.2.2.0

[ORM1995]

Hello!

I am working with the ESP-12 module (ESP8266) with the factory AT firmware.
In the initial state, the module responds to basic AT commands, for example:

AT
OK
+CIPSTAMAC:"ec:64:c9:f4:44:96"
OK

I need MQTT support for work, so I decided to update the firmware to version ESP8266 AT Release v2.2.2.0 (archive ESP-WROOM-02-AT-V2.2.2.0.zip).
I flash it using the ESP8266 FLASH DOWNLOAD TOOL v3.9.9_R2 utility.

Files and addresses that I use when flashing:
bootloader.bin 0x00000
partition-table.bin 0x8000
ota_data_initial.bin 0x9000
esp-at.bin 0x10000
at_customize.bin 0xF0000

I don't use the factory_param.bin (0xF1000) file on purpose, to save factory settings (MAC, calibration, etc.).

Problem:
After flashing, the module does not respond to AT commands.
When I turn on the UART, I see:

ets Jan 8 2013,rst cause:2, boot mode:(3,6)
load 0x40100000, len 7464, room 16
tail 8
chksum 0x34
load 0x3ffe8008, len 24, room 0
tail 8
chksum 0xbd
load 0x3ffe8020, len 3340, room 0
tail 12
chksum 0xf9
csum 0xf9

If you flash factory_param.bin at 0xF1000, the situation does not change.
If you restore the factory firmware from the backup, everything works.
Questions:
What is the correct scheme for flashing ESP-12 modules (ESP8266) for AT commands version v2.2.2.0?
Do I need to flash factory_param.bin for compatibility with the new firmware?
How to correctly save and restore factory parameters (MAC, calibration, etc.) during an update?

Thank you!

[pieterc]

It could be that the firmware is using the wrong pins for TX and RX. See here:
https://docs.espressif.com/projects/esp ... odify-uart

Example:
python at.py modify_bin --tx_pin 1 --rx_pin 3 --rts_pin -1 --cts_pin -1 --input ESP-WROOM-02-AT-V2.2.0.0\ESP-WROOM-02-AT-V2.2.0.0\factory\factory_WROOM-02.bin