Hehe, got root. Huge huge thanks to @flipflop139874 for the help.
Noticed some weird stuff. e.g you should intercept the first request and leave the second one go forward without any intervention.
had to reset the box couple of times cause of the cache.
prior MITM knowledge is really handy for root on this box.
you have to find alternatives for some stuff explained in online articles.
and thank you @jkr for the box.
as usual if anyone need help, PM me.