solved this issue! c860 seem to have different ways of accessing the service menu, mine let me in after the following:
1) remove charging cable
2) move battery switch to open
3) remove battery
4) wait 30 sec.
5) press d & m at the same time and keep them pressed
6) insert battery - at this point my service menu appears alredy on the screen without closing the battery switch
7) close battery switch, insert charging cable for safe flashing