If you have switched the 360 off either at the plug or the switch on the back of the box waited for a few minutes and it doesn't start up and you have checked all the connections then it's probably faulty.
You can either call Virgin on 150 from a Virgin phone, mobile or landline, or 0345 454 1111 from any other phone to report a fault, or wait here for one of the forum team to pick this up which might be 2 to 3 day's. When phoning choose the option to report a fault, then ignore all the options offered and you should then be placed into a queue to speak to someone.