I have een some great suggestions.
Here is mine.
start over.
use your 5 senses.
give it an extreme visual inspection,
smell the unit, .
feel the unit, etc
Then, check your power supplies, both main and local, ( in any
suspected areas)
Get the manual.
Use sympton analyisis diagnosis to narrow your troubleshooting.
If you have a PIP board, suspect that. (and or component therein)
Tuner possibly, and whatever video switching
devices/circuits would be suspect as well.
Looks like a possible "crap"-acitor hunt

...finals...
...kids...


those may play a role
good luck