Yellow troubles

[clear flare]

I have an ha yellow and the idea was to completly reset the thing. well that was not a big succes
It won't boot anymore, i did use an usb cable and rpi boot to acces the device and wrote new files om the yellow. (a map with the files opened on my window machine). but still no joy
while starting green and red led is lit and after some time green led wil go out. yellow led is never lit

any idea what to do?

[tiny acorn]

What does it show on the serial port?

[clear flare]

to be honest, i checked with putty and nothing

even update with an usb stick doesn't work. the yellow led stays off all the time