Toshiba smart tv picture flashes on and off still I changed both boards inside tv

Your TV might of had stopped working and has died on you and you should by a new TV than to try and fix the TV that is broken.

Your EEPROM has some bad files on it. It's an expensive IC to chance if you have the equipment and knowledge to replace it, other option is replace the main board

is it smart or normal if normal can solve this issue but smart is too much diffficult with out replace mother board

I need help my tv isn’t playing any sound please help!!!

Those 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://homenol.blogspot.com/
http://electronicshelponline.blogspot.com/
If blinks continue without any pause, the main board is faulty.
Search the site by type in the "brand name" to your device, [Exclude the model number] in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.
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change the main board

did you change power supply? how many times does light flash (red) you didnt change the power supply did you use a vom on connections?

We Are Here To Help !!!
Donal Deane MCSE,ASE,CPO

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 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://electro-medical.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.

The 42RV530U is known to develop problems in both the power board and the main board. You can check out our power board repair service at
http://www.coppelltvrepair.com/p/442/repair-service-for-toshiba-42rv530u-power-board-75010942-dead-tv-or-clicking-on-and-off-problem
and I'd also recommend that you search for 42RV530U at http://blog.coppelltvrepair.com as we will eventually release an article on how to test the board.
Hope this helps.