NodeMCU v3 doesn't boot

A few weeks ago, I ordered my 1st pair of sensors.
The 1st one worked just as expected and a week ago I finally got around to finish the setup and it has been working flawlessly ever since.
The 2nd on the other hand didn’t work out-of-the-box. Besides the LED flashing and the sensor fan spinning, it indicated zero activity.
So I tried to troubleshoot it - but it shows zero output when connected via USB compared to the working one which just does what I’d expect.
So I assumed the supplier possibly forgot to flash it, so I flashed it using flashlatest.sh

$ esptoolpy=$(which esptool.py) esptool=$(which esptool) ./flashlatest.sh 
usage: [esptool=/path/to/esptool] [esptoolpy=/path/to/esptool.py] [devserial=/dev/ttyUSB0] ./flashlatest.sh
writes output to listofflashed.csv
devserial=/dev/ttyUSB0 # define to change
nodemcuID       sensorname      hexchipID       MAC     revision:serial email   lat     lon     locationaddress sensorID1  sensorname1     sensorID2       sensorname2

esptool.py v3.2
Found 1 serial ports
Serial port /dev/ttyUSB0
Connecting....
Detecting chip type... Unsupported detection protocol, switching and trying again...
Connecting....
Detecting chip type... ESP8266
Chip is ESP8266EX
Features: WiFi
Crystal is 26MHz
MAC: a8:48:fa:ce:ae:9b
Uploading stub...
Running stub...
Stub running...
Chip ID: 0x00ceae9b
Hard resetting via RTS pin... 0x00ceae9b 13545115
ask more infos? [y/N]
DBID    esp8266-13545115        0x00ceae9b      a8:48:fa:ce:ae:9b
a8:48:fa:ce:ae:9b       :       @       LAT     LON     LOCADRESS       SID1    SNAME1  SID2    SNAME2
--2021-12-25 01:52:19--  https://www.madavi.de/sensor/update/data/latest_en.bin
Resolving www.madavi.de (www.madavi.de)... 2a01:238:42ae:3700:ef20:a9d0:cefd:73e9, 85.214.62.33
Connecting to www.madavi.de (www.madavi.de)|2a01:238:42ae:3700:ef20:a9d0:cefd:73e9|:443... connected.
HTTP request sent, awaiting response... 301 Moved Permanently
Location: https://firmware.sensor.community/airrohr/ [following]
--2021-12-25 01:52:19--  https://firmware.sensor.community/airrohr/
Resolving firmware.sensor.community (firmware.sensor.community)... 2a01:238:42dc:ad00:8cc3:f820:67f4:ff2d, 81.169.210.193
Connecting to firmware.sensor.community (firmware.sensor.community)|2a01:238:42dc:ad00:8cc3:f820:67f4:ff2d|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 1958 (1,9K) [text/html]
Saving to: ‘latest_en.bin’

latest_en.bin                100%[=============================================>]   1,91K  --.-KB/s    in 0s      

2021-12-25 01:52:19 (100 MB/s) - ‘latest_en.bin’ saved [1958/1958]

flash now? [Y/n] y
to erase SPIFF (config data) use arduino IDE and https://github.com/esp8266/arduino-esp8266fs-plugin
see https://github.com/esp8266/arduino-esp8266fs-plugin
or overwrite SPIFFS now? [y/N] y
esptool v0.4.13 - (c) 2014 Ch. Klippel <ck@atelier-klippel.de>
        setting board to nodemcu
        setting baudrate from 115200 to 115200
        setting address from 0x00000000 to 0x00100000
        setting port from /dev/ttyUSB0 to /dev/ttyUSB0
        espcomm_upload_file
        espcomm_upload_mem
opening port /dev/ttyUSB0 at 115200
        tcgetattr
        tcsetattr
        serial open
opening bootloader
resetting board
trying to connect
        espcomm_send_command: sending command header
        espcomm_send_command: sending command payload
trying to connect
        espcomm_send_command: sending command header
        espcomm_send_command: sending command payload
        espcomm_send_command: receiving 2 bytes of data
        espcomm_send_command: receiving 2 bytes of data
        espcomm_send_command: receiving 2 bytes of data
        espcomm_send_command: receiving 2 bytes of data
        espcomm_send_command: receiving 2 bytes of data
        espcomm_send_command: receiving 2 bytes of data
        espcomm_send_command: receiving 2 bytes of data
        espcomm_send_command: receiving 2 bytes of data
Uploading 3125248 bytes from empty.spiffs.bin to flash at 0x00100000
        erasing flash
        size: 2fb000 address: 100000
        first_sector_index: 256
        total_sector_count: 763
        head_sector_count: 16
        adjusted_sector_count: 747
        erase_size: 2eb000
        espcomm_send_command: sending command header
        espcomm_send_command: sending command payload
        setting timeout 25916
        setting timeout 1000
        espcomm_send_command: receiving 2 bytes of data
        writing flash
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starting app without reboot
        espcomm_send_command: sending command header
        espcomm_send_command: sending command payload
        espcomm_send_command: receiving 2 bytes of data
closing bootloader

…but it’s still the same - the output in Minicom is absolutely zero (same connection params, same cable etc as the working one).
Can anyone point me to resources on how to debug this further?

Please use the flasher. Look at the instructions in the website.
Is it a normal SC Sensor ?