There are no customer accessible diagnostics. Only customer services can use these.
The HDD used in TiVO's are hard encoded to the boxes, & cannot be interchanged. You will be able to transfer your series links, but any recording will be lost. Don't forget, Virgin's equipment is rented. You don't own it.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV+), Talk Unlim Telco, VIVID 100, Virgin PAYG Mobile