Where can i buy or order the main board for my led tv? and how much will it cost me? its a sansui sled3215. i would greatly appreciate it if anybody can help me. thank you

Not sure what your asking

Panel lock Open with remote control

Wow, a master replied, if you need to buy TV accessories, you can take a look at this website:www.abctay.com

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Sounds like The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts. http://electro-medical.blogspot.com/ It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.
Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.

Sounds like it can be because of the faulty LED's. The LED is drawing over current for the power board that's why the fault arise again. There would be no fault in main board or the TCON board.
If you wish to get some details; check the site linked here. Pull up older posts.
http://electro-medical.blogspot.com/

IT is not wise to attempt repairs on LED TVs. They rarely work, and you end up replacing the unit anyway. The newer units have the LED drivers connected directly to the LED screen and there is no way to repair/replace them. Board swap/replacement is tempting, but overall the lost time versus the cost is often not worth it. Sets today are only designed to last 3-5 years. The manufacturers use the minimum rated electronic parts to ensure failure and thus a steady stream of replacement buyers. Some don't even make it out of warranty, but the manufacturers are willing to risk the cost in order to ensure that the planned obsolescence continues. Gone are the days of a set lasting 10-12 years or more. Take that into consideration when buying a replacement and only get what you need. Buying newer features that are not in full use yet only costs more and by the time you get the benefit of them, its time for another new set.

You'll have to replace the main board of your TV. You can get the part from here: TV Parts Universal TV Stands DLP Chips ShopJimmy

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
Some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement.

The main digital board stopped working. No SCL, SDA. Contact any service technician.