SXT FALL DOWN..... help for reinstall sxt

hi every body
i have number of sxt .. one part by any way there is no routeros on it and no soft ..
trying to reset it and also no result
dont give me sound for working soft and no thing in win box

my question :

how to upload routeros to sxt like we reinstall other products by netinstall???

plz A detailed explanation of way

thanks for all

The issue is resolved

thanks for all