This TV had no front LED and Sony’s tend to have diagnostic blinking codes. Probing the power supply board connector found STBY3_3V, AC_OFF_DET and POWER_ON signals present but REG12V missing. The block diagram shows 12V is regulated down to 5V for the main board and processor and no 12V is a power supply board fault. Training and service manuals can be found here. Schematics here.
I was looking for points to measure the PFC voltage and stumbled on R6536. The negative side can be contacted on the jumper FB6501/JS6502. I measured 394VDC on one side of the resistor and nothing on the other side indicated the resistor was blown.
Searching this resistor designator found similar boards where shorts on Q6101 and Q6102 (2SK4096LS) would cause R6536 (fusible 0.47 ohm 1/2W) to blow.
Replacement parts ordered from Digikey were FDPF8N50NZ-ND (500V, 8A, N-CH, 0.85ohm, TO-220F) and PPC.47BCT-ND (0.47ohm, 1/2W). T-220F is an insulated package where the FET contacts the heatsink.
After replacement, the TV powered up. If the fuse blows again, it is recommended to check the components feeding the gate of both mosfets.
Power supply part number is APS-260(CH) 147420511 1-474-205-11