My 32" hannspree was working this morning. Shut it off for an hour and on turning back on the sound is ok, but the picture cycles through blue, green, red, white full screens.

Change input device to some other like a DVD player and see.
Switch off TV, switch off power, remove plug and wait for 48 hours and retry.
If problem persists, call in a qualified service technician.

Try to reset by removing power cord for a while and plug back and see what happens.

Go to your On Screen Menu to picture settings and reset and choose "reset picture" mode. This will bring you back to factory defaults. If this doesn't work shut off wait 10 sec. and turn on the TV. If still no luck call your best friend who is a TV repairman, you probably have a damaged blue drive.

How old is the tv

I would get the TV replaced under guarantee. There maybe a loose wire in the power supply or invertor stages that is arcing and burning

It sounds to me like it's stuck in service mode.There is a button combination with the remote to return it to normal. I would call Vizio support and they should be able to help you.

I think it's a combination like [volume -], [channel -] and power but I could be wrong.

needs resoldering, in the heated areas, such as, crt socket board, power area, and high voltage area....it will be back to normal...

If the TV still switches on, and you get sound, then it could be 1 of 2 things.

The PSU, less likely.
The Inverter, more likely.

It is difficult to determine which is faulty without some test equipment etc.

I hope that helps.

I had a similar problem with my HANNSLounge 32", the screen switched on with green light but none of the front panel buttons worked (screen is black apart from showing the input source in the top left).
After powering off numerous times I tried starting up with a blank SD card in the reader and the tv cycled between red green and blue screens and then reset itself. (Some sort of firmware restore?) After which point I had a working screen again! (Will have to see how long it lasts for!)

Unplug it from the wall, wait 2 minutes and plug it back in. if problem still exists, its probably the main pcb.