Hi @seriousStuff and it appears we are stuck with some serious stuff to deal with! ;-)
I'm going to collect a bit more detail for others to resolve which will save some time in the
back-n-forth that they would have to do.
'I tried to flash the firmware, for that I use the Flasher tool'
Different tools, different processes, different OS's, etc
Q1: Could you explain which tool and/or process along with PC environment/OS please?
Q2: Which version is being flashed and by chance do you recall what version was there, ballpark okay? One of these perhaps, or some other file?
Q3: Was any attempt made to try the 'Advanced Reflashing' ?
Q4: Was an attempt made to flash directly from the WebIDE?
Upper Right :: Settings >> Flasher
I tried to flash the firmware, for that I use the Flasher tool.
After entering the bootloader mode the red and the green LEDs pulse alternating. After a few seconds both LEDs are brightly lit.
The documentation (https://www.espruino.com/Troubleshooting#on-the-espruino-pico-wifi-boards) says that this might have to do with a bad cable, but I'm getting the same result when I'm plugging the board directly into my computer.
Any idea what I could try additionally?