How do I fix my KDL55HX750? It will not turn on. No sound or picture. Just 3 blinking red lights. What should I do next?!?

The red light flashing is indicating the error.
depending on the make and model of the TV, the duration of the flash and number of flashes determines the error code.

My TV continues to blink on Standby with Red light ...

https://community.sony.com/t5/...blink...Red-light-flashing.../59141

Jan 12, 2013 - I need help with my Sony TV. The red flashing light keeps going on and off. ITs on standby. can someone guide me as to how to fix the problem. ... I have a Bravia KDL52W3000 with a 7" wide dead pix... Television - Picture & Sound ... What is the exact model number of the Sony TV? Check if the same issue ...

there is main board defective please replace the main board 3 time blink is dc alert which is happened in side the system ic & we cant replace the system ic so we replace complete main board

How many times this standby/power light blinks at one time switch ON? Count it carefully. These blinks are fault indication, and known as blinking codes. From the number of blinks occur at one time switch ON; you can get an idea about the faulty circuit stage inside the TV. This will make repair easy.
If you're sound in electronic, and wish to get more details, check this link. http://electronicshelponline.blogspot.com/ Selecting the view option, either to Mosaic / Time slide, can be selected by the drop-down list, at the top left of the display window, will make surf easy. You can also do a search, by type in the brand name/model number/IC used, in the search box at the top right of the display window.
It sounds that the TV is mew one, and come under warranty period. If so, it will be best to get it repaired by the authorized service center for Sony.

Hi,
Question shows tv is Sony KDF-60WF655.
Green light blinks when tv gets prepare to fire up lamp, check internal circuits then show picture on front screen.
Red light blinking shows some kind of internal problem during circuit check and protection got activated upon some failure.
Count the red light blink as you will see 3 second long pause and post it here to diagnose what section of tv got problem.
Did you replaced its lamp in last 2-3 years?
Thanks.

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How many times red light blinks when TV lost picture? There would be interval of 3 seconds in red light blinks so count pause to pause and let me know.

Thats great, Please rate solution.

I have a 36 Trinitron, the sound and picture went but the red light just keeps blinking, any ideas? Please ....

Sony has a code for those blinks indicating the problem area. Count the blonks till the pause then google Sony blink codes for the area to fix.