Hi,
Sony has self-diagnostics built-in to the TV. This is as you noted indicated by the blinking LED light(s). Initially and based on conventional TV sets, the four (4) blinks a
vertical failure. This would normally mean the vertical IC requires replacement. In some Sony versions/models, the IC would be LA7835 but this has to be confirmed on the actual part from the PCB. There are instances where the IC is not defective but the diode and/or limiting resistor from the FBT that provides the ~+28VDC supply to the vertical IC that could be defective. As you will note, this is rather a technical repair and not an easy user action. This of course would require a familiarity of electronic components/circuitry and safety procedures, use of a DVM and a soldering iron. It would be to your added advantage access to a
service manual or at the very least a schematic diagram with voltage readings. Should you be uncomfortable performing a DIY (
do-it-yourself), perhaps your best bet would then be to seek the services of a qualified professional.
Hope this be of initial help/idea. Pls post back how things turned up or should you need additional information. Good luck and kind regards. Thank you for using FixYa.