Samsung LN40A330 will not power on. LED on power button just flashes steadily. Power cord is good. Any ideas?

Your issues come from the hot side of the power supply. You can replace the power supply and it should work again or if your capable of repairing it yourself you can do that for a few bucks. below is a link for a new PS, also shopjimmy.com would have one
Samsung Power Supply Board BN44 00772A for UN60H6203AFXZA eBay

Interesting, sound like a failure of the button because most system either work with a greeg lit up led or fail with an amber or orange lit or flashing.
In this instance the amber could mean something has gone bad but the fact you can hold the button and have it boot up is strange.

Does the led turn green after holding the button for a while to let the machine boot?

regards,
mike

Yes,the fuse in the power supply board,that the board,where the power a/c cord plug into it.Check ur power source?Yes,than the tv power supply board is dead.These modern circuit boards design never kill the fuse that easy.Tries websites like Shopjimmy.com,Ebay.com to buy a whole refurbish power supply board for the replacement.

Tries unplug,replug the tv it back like an hour later.The tv now should,resetting itself back to the factory setting.The tv now should work.Not,than the power supply board is dead.That the board,where the power a/c cord plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a whole refurbish power supply board for the replacement.

How to fix it.....
It totally worked for me....
http://www.youtube.com/watch?v=Mm51C_RDIZE

I think you have more than one problem there. Take it to a local PC repair shop and have them check it out. Five years is a good age for a computer though so you may want to think about buying a new one. Best of the Irish Luck to yer.

Thanks, but the problem fixed itself. After leaving the scanner on for a very long time, the LED finally started to glow steadily. Now after power cycle it only takes a few seconds to become ready.

ITS BROKE - YOU HAVE TO GET IT FIXED OR THROW IT OUT. SAME THING HAPPENED TO US -UNDER WARRANTY BUT WE HAVE TO PAY THE $80 TO SHIP IT TO THEM. WHAT A FARSE.

This flashing LED usually means only two things, both are quite harmless:

1. Some laptops will flash the power LED when battery is charging. If this is the case, it should stop when battery is fully charged. This can be presumed if the laptop starts normally while LED flashes. If not, suspect step 2 below:

2. Your laptop is either "asleep" (suspended) or in "hibernation" mode.It does this if left for a long time with no activity/input from you. You must simply "wake the laptop up" now:

Look for a symbol on keyboard for "sleeping" (like a half moon with zzzz) and press that key WITH whatever color coded key matches the symbol color (usually "FN" key). If there is no suchkey, press the space bar and hold it down a few seconds.

Then wait. Can take 60 seconds to "wake up" on slower processors.

If this does not work, press AND hold the POWER button for 10 seconds. Then wait 60 seconds and press power key again, briefly, to start laptop normally.

Pressing and holding the power button 6-10 seconds forces a complete system shutdown.

If this happens often, something may be wrong with APM or ACPI settings/driver. You can go to start menu/settings/control panels/power management and adjust settings (or disable sleep/suspend and hibernation if all else fails to resolve situation)

good luck.