I have a Sharp 70" (LC-70LE632U) LED TV. When you turn it on, the front led is on, but no screen. After a few seconds, the front led starts 5 short and 2 longer blink and continue this way constantly.

1)Remove Mains Plug. Press Standby button from LED Panel for 30 second.

2) Press Input & Ch.Down Switch from LED Panel both together.

3) Insert Mains Plug and switch on led tv keep both switch press.

4) "K" will appear on screen

5) Press Ch Down & Vol down switch from LED panel.

6) Page 1/10 will appear on screen

7) Go to 9/10 by pressing up & down arrow from remote

8) Select EEP Cleared and press ok button from remote.

9) Remove plug and checked LED is working or not.

These blinks [flashes] are fault indication (Error Codes). From the number of blinks occur at one time switch ON, you can get an idea about the faulty circuit section inside it. This will make repair easy. These are called blinking codes. Make sure about the exact number of blinking of the standby/power LED, by switching On & OFF the set, for at least two times. Count it carefully. If you wish to get some details, check the site linked here. It has details about blinking codes, and fault locating procedure, to many popular brand TVs and other devices
http://electro-medical.blogspot.com/

Blinking codes details of many popular brand TVs are given. Surf the site with patience. If blinks continue without any pause, the main board is faulty.
Counting of number of blinks to Philips TVs is entirely different to that of other brand TVs. It is not a direct count procedure. The site have details about how to count the number of LED blinks [Fault Codes] to Philips brand TVs are given; along with details of the faulty circuit location