I know each mod is different (I think some have manual switches, others swith chip off when you open dvd etc). Mine is a xenium chip (through premodded.com). There isn't a manual switch. It has an LED, which I thought indicated whether the mod was on or not, but when playing a game from the HD (therefore mod on I assume) the LED can be either Red or Green, depending on whether I booted into avalaunch or evox. The 'original bios' option from the start up menu fails to load, with the message 'Your xbox requires service. Please call customer support'. EDIT - this bit has been sorted, thanks to an increadibly quick reply frpm premodded. The HD wasn't locked, and it has to be in order to go into the original bios. I can go into the Microsoft Dashboard (and therefore live) via evox, but I don't know whether the chip is still enabled (not sure if this gives an indication, but the system reboots if I press both triggers, black, and the back button). Any ideas Thanks!