First the green LED is solid, then goes in and out. It has never done this before except on a reboot I did remotely. I tried 3 different power supplies, and it is still doing the same thing. I tried the sd card, and it works. Nothing gets displayed on the screen using the hdmi output.

OK, The "green" led is solid? My Pi has three green leds when I power it up so you'll have to give more information.
When Powered up, the red PWR led comes on and the OK led flashes green. (I actually assume this is the one you mean but I've got green FDX and LINK ones as well - OK, OK, so I'm just being picky but we can't guess or you'll get a duff answer)

The other bit you haven't mentioned is what you've got connected to the Pi?

Can I assume it worked OK before?
The SD card works? What are you testing it on? The OS MUST be for an ARM chip, preferably from the Raspberry Pi site, an x86 distribution won't work. (You already know this but we need more info to help.)
What OS distribution are you using?
Did you add any USB devices just before it stopped working; USB disk (Not a pen drive, one with a spinning disk)? Maybe not enough power?
Will it boot with NO USB devices attached?
What is your HDMI connected to; Monitor via a DVI cable and adapter, TV?

That'll do for now, I'm being summoned to the pub!

Play Bonny!

Yes it worked before and the Only green LED that is flashing is the ACT one. I connected the raspberry pi to a digital tv. I tried it without it also, and it did not work.

Find a picture of your exact card, post the link and those of us with similar can offer suggestions.
The makers seem to think insufficient power is the main issue people have. What is the current rating or wattage of those power supplies?

Two are 5.1V with 0.7A, and the other 5.0V with 0.7A. It is model B and now the other light does not flicker anymore, and the red LED is the power indicator.

A picture might be hard if I don't have a camera, I will have to borrow one.

Google Image Search

No, don't go to any sweat - just have a look and find one that's exactly like yours, and post the link. I think I have the model B but I have it in a box and only ever see a blinking red led.

It looks like you've probably enough power to me. Mine runs with a 5V 160mA Nokia phone charger, you've got 700mA to play with!

You didn't answer most of my questions though! I now know it worked before but nothing about your SD card and distribution. Have you built a new SD card and tried that? If I pull my SD card I just get the red led and no display. Powering it up I get a slight delay before I get video so is your OS corrupt?

What USB devices have you got attached? I've just got a wireless dongle for my keyboard/mouse

@ business kid

Model Bs have a network connection, as far as I know there are very few model As (which don't have one) if at all yet

Play Bonny!

Boot your sd in a VM to see if it works ...

The power supply needs to be stable as well. If it drops below 700mA while booting, it wont work either.
Could you provide more info about the one(s) you're using.

@ Soadyheid: ...160mA with ethernet...??
The ethernet connector is what takes most power (it's actually on the usb bus as well).

Model B owners using networking and high-current USB peripherals will require a supply which can source 700mA (many phone chargers meet this requirement). Model A owners with powered USB devices will be able to get away with a much lower current capacity (300mA feels like a reasonable safety margin).
http://www.raspberrypi.org/archives/260

To clarify the only one that is red has been red since the start of the issue, it was the ACT one that was flickering at one point.

Yeah I used 3 phone chargers for this.

I think it is the device itself that is going out, so does anyone know how to exchange/return one of these things?

You don't get things sorted that way.
If you read through the thread and try to answer the questions you have been asked, you'll be a lot nearer sorting your problem.

The SD card works, and so does the OS on it.

What do you see when you connect a screen and boot it? Or have you set "Quiet" everywhere? I always leave that stuff there so I see the kernel hangs.