No output – sound from your AV receiver
Most often when you have no sound but the receiver still turns on this means either power supply or more likely blown outputs on the final amplification stage. Spending half of what it would take to buy a new one is a mistake. The exception would be a high end unit- which should only be serviced by the manufacturer.
Lines in your TV screen
This is caused by one of two or more reasons but all problems will fit into one of these categories. Either the screen is bad or the drivers which run the screen are bad in either case repair can be hazardous to your well spent money. If the TV is over 5 years old replace automatically.
No sound from your Cable box
Make certain that you go into the setup in some cases advanced setup and check the Audio setting. It will need to be in the HDMI setting. ALSO always unplug (reboot) your cable/Sat. box for ANY problem. This fixes more than half of all malfunctioning units.
Blu-ray player no longer works WI-FI
Wi-Fi is a most definite weak spot in Blu-ray players and my guess is it will be in many other devices including media players and smart TV product. If other devices have no problem working i.e.: your mobile phone on the internet playing back u-tube for instance (make certain to shut off your DATA on your cell phone as it is near impossible to determine if your phone is working in DATA or WIFI). If in doubt buy a new Blu-ray player and see what happens. Never consider repairing a Blu-ray or DVD player.