1. You get your service manual out for the TV on your bench.
2. Follow the flowcharts for what to replace for the symptom.
3. Keep notes about the parts used and
4. Return the working set along with the time spent and parts used to the front office.
There are folk that are new to repairs and may try to do without service manuals and parts but those folk tend to have a lot of problems getting the set fixed.
Did you try AVSFORUM where a lot of non-electronic techs go?