The samsung ln46a650 will click continously when triing to turn on and the red light just keeps blinking.

Most likely failed capacitors in the power supply. I am currently having the same problem with my 26 month old LN46A750. Samsung has greed to fix this as a "courtesy repair".

http://www.thebuzzmedia.com/samsung-tv-capacitor-clicking-issue-and-free-repair/

http://www.avsforum.com/avs-vb/showthread.php?t=1198409

As others pointed out In most cases it is the capacitors in he power supply section that have gone out.

Common symtoms are
-shuts down
-takes a long time to come on
-relay clicks
-dead set

You can get capacitors online or you can get a complete kit with instructions and support from www.TvRepairKits.com . Its a failry easy DIY fix.

Upper right corner of the power supply board
Look for bulged tops on:
CM851 1000uF 25V
CM852 1000uF 25V
CM854 1000uF 10V
CM855 1000uF 10V

Make sure to install new capacitors with correct polarity

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://electronicshelponline.blogspot.com/
Blinking codes details to many popular brand TVs are given. Surf the site with patience.
If blinks continue without any pause, the main board is faulty.

Hi Friends,
Some time back I repaired a 46" Samsung LED TV with continuous relay clicking and blinking red LED. Power on 5V line was short with the ground. I had to replace the main board in that case. I hope this will help.