HP spectre x360 laptop doesn't turn on and power button blinks once every 3-4 seconds

[SAM_90]

HP spectre x360  model 13-aeo12dx, power button LED blinks, so the pattern is LED is ON for 3 seconds and Off for 3 seconds, and the laptop doesn't turn on, no fan sound and no other indication, and blank screen. When I tried to charge with laptop power off, it does charge completely, but when try to charge with power on then both the power LED and charging LED blinks in sync, once in 3-4 seconds and the pattern is  again same, basically both the LED's are ON for 3 seconds and Off for 3 seconds, and it does continues forever.

Tried most of the solutions, 

1. Remove the battery, press and hold the power button for 15 seconds, reinsert the battery into the compartment, and then continue to the next step.

2. Press and hold the power and the Mute buttons at the same time for 15 seconds or until the computer restarts

3. Removed the Memory module, cleaned it up, drained the battery and restart. 
4.  Press and hold Windows + B key with power button for 2-3 seconds, still no luck.

Tried all the solutions but still facing the same issue. Please help!!

[Huffer]

Dead motherboard. You have tried everything else to do.