Panasonic TC-P50S60 Technical Manual page 67

These conditions can cause the TV to shutdown and the power LED to blink 10 times
1. A board defect (SUB3.3V or SUB5V is overvoltage)
2. Wrong diagnostic by the A board
== Easy Measurement Point ==
・SUB3.3V is applied to 3 pin of A1 connector via SUB_AI_3.3V.
・SUB5V is applied to 1 pin of IC8602/8603 (USB switch IC).
If SUB5V or SUB3.3V has overvoltage, the Q8771 becomes active. So, STB3.3V flows to IC8000.
When the IC8000 detects 3.3V level, it occurs to shutdown TV and to blink 10 times for power LED.
SOS Detect Circuit Explanation
IC8602/8603
A1
3
1
A
AK16
IC8000
PARAGON
Slide 67