that's Froggit - and the Froggit version of the manuals in German is sometimes unfortunately not always helpful and misses important points.
On the other hand, otherwise, we wouldn't need such a thread like the MUST READ.

I quote from our thread - chapter 3.a console firmware:
console/device firmware update for the HP2551 and HP350x consoles is done via microSDcard. Download from Ecowitt.com or ambientweather.net [https://help.ambientweather.net/help/ambient-weather-ws-2000-firmware-download-center/]. Copy the file user.bin (HP2551 or clone) or firmware.bin + picture.bin (HP350x) or factory.bin (WS-2000/WS-5000 console) to the FAT32 formatted SD card's (
SDHC type only max 32 GB
) root directory on a PC and insert it into the console. HP350x will need a power-cycle [switch off/on].The microSD card can only be properly inserted in one direction. Looking at the console display, the contacts of the microSD card have to go in first and have to be visible for you, the printed side of of the microSD card will have to show away from you.
If you know German, you can also read
https://www.wetterstationsforum.info/wiki/doku.php?id=wiki:wetterstationen:ecowitt-stationenAdmittedly you have to look under firmware update for the HP2551 console in the meanwhile largely grown MUST READ thread, where the SD card issue is mentioned.
Anyhow - the English manual mentions the SD card and indirectly also the SDHC (via the 32 GB limitation). It could be clearer - no objection.
I have already asked Ecowitt several tims to include this information into the HP2551/HP2560 console or station manual, but so far it hasn't happened. And Froggit are rather resistent against suggestions "from outside".
The solution will be a SDHC card e.g. enter "SDHC 32GB micro" into the search field of
https://www.amazon.de/