I have a 52'' samsung and when you plug it in it just keeps clicking on and off. i let it do it for about 4-5min and it turned on but the picture was shaky and only black and white.

That tv is very common for power supply failures. there will be several bulging vented capacitors on the power board. the capacitors are used for filtering in the power supply so they would smooth out the ouput of the certain switched supply circuit they are part of. easiest way would be to replace the power board otherwise with some minor soldering skills replacing the capacitors is cheapest route. the capacitors are near the top right corner of the power board which looking from the back of the tv is the board on the left. usually there are about 5 capacitors total that need to be replaced.