[CBU/BK7231N] AVATTO WSM16-W4 4-Gang WiFi Relay Module teardown and firmware flash

{
   "rl1_lv":"1",
   "onoff_clear_t":"10",
   "net_trig":"2",
   "netled1_lv":"0",
   "onoff_rst_type":"2",
   "ffc_select":"0",
   "total_bt_pin":"8",
   "nety_led":"2",
   "total_stat":"0",
   "remote_add_dp":"49",
   "remote_list_dp":"50",
   "module":"CBU",
   "inch_en4":"0",
   "onoff4":"22",
   "inch_en2":"0",
   "inch_en3":"0",
   "inch_en1":"0",
   "onoff1":"14",
   "onoff2":"16",
   "onoff3":"23",
   "rl2_pin":"17",
   "series_ctrl":"0",
   "cyc_dpid":"43",
   "rl1_pin":"20",
   "rl4_lv":"1",
   "on_off_cnt":"10",
   "onoff_rst_m":"1",
   "rl3_pin":"9",
   "rl3_lv":"1",
   "rand_dpid":"42",
   "onoff_n":"3",
   "rl4_pin":"28",
   "jv":"110.0.2",
   "reset_t":"5",
   "netled1_pin":"6",
   "rl2_lv":"1",
   "net_type":"0",
   "inch_dp":"44",
   "ch_cddpid1":"9",
   "clean_t":"5",
   "init_conf":"38",
   "zero_select":"0",
   "onoff_type":"0",
   "ch_cddpid4":"12",
   "ch_cddpid2":"10",
   "ch_cddpid3":"11",
   "total_bt_lv":"0",
   "ch_num":"4",
   "ch_dpid3":"3",
   "ch_dpid4":"4",
   "netn_led":"2",
   "ch_dpid1":"1",
   "ch_dpid2":"2",
   "crc":"78"
}

Device configuration, as extracted from Tuya: 
- Pair/Toggle All Button on P8
- TglChannelToggle (channel 4) on P22
- TglChannelToggle (channel 1) on P14
- TglChannelToggle (channel 2) on P16
- TglChannelToggle (channel 3) on P23
- Relay (channel 2) on P17
- Relay (channel 1) on P20
- Relay (channel 3) on P9
- Relay (channel 4) on P28
- WiFi LED on P6
Device seems to be using CBU module, which is using BK7231N.
And the Tuya section starts, as usual, at 2023424

{
  "vendor": "Tuya",
  "bDetailed": "0",
  "name": "AVATTO WSM16-W4",
  "model": "WSM16-W4",
  "chip": "BK7231N",
  "board": "CBU",
  "flags": "0",
  "keywords": ["Allegro"],
  "pins": {
    "6": "WifiLED_n;0",
    "8": "Btn_Tgl_All;0",
    "9": "Rel;3",
    "14": "TglChanOnTgl;1",
    "16": "TglChanOnTgl;2",
    "17": "Rel;2",
    "20": "Rel;1",
    "22": "TglChanOnTgl;4",
    "23": "TglChanOnTgl;3",
    "28": "Rel;4"
  },
  "command": "PowerSave 1",
  "image": "https://obrazki.elektroda.pl/1384267700_1736605394.jpg",
  "wiki": "https://www.elektroda.com/rtvforum/viewtopic.php?p=21388042"
}