Tracing TVI to its' "entry point" can, sometimes, take you round in circles because of a forgotten step. This step-by step process guides you through that maze and leads to the answer or solution in a logical manner.
You will be asked you to do a specific action then questioned on whether the TVI has cleared or is still present (or some other question).
On answering the next logical step is given, the fault diagnosed or a solution given.
Some operations should only be carried out by people who know what they are doing and have the relevant schematic to hand, there are voltages/currents inside televisions that can kill.