The sound on my Digihome TV keeps going off and only returns by switching the set off then back on again. Any solution ideas please

Have you tried checking in the menu to see if wi-fi has been enabled? If it has, it may be looking for a dongle and is stating it is missing. Perhaps disabling wi-fi will cause the notation to be removed.

return for replacement or repair if try to repair or tinker with will void any warranty or return policy

Sounds like main board fault. 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/

Audio output IC overheats. Check and replace the damaged component/s at its audio output section circuit board. If needy, replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. Surf the site with patience. Do a search by type in the brand name of your device at its search box.
http://electronicshelponline.blogspot.com/

Sure are you using a preamp component system or do you want to play it on the tv if you do have a pre amp run the RCA cables to sterio input on amp or aux then in the setting of the amp go into sound and put the aux to 6.1 also remember that to use audio out on your tv

Count the number of flashes occur at one time switch ON. These flashes are called blinking codes; and are fault indications. Form the number of these blinks, you can get an idea about the faulty circuit stage inside the TV. If you wish to get more details about these blinking codes, check the site linked here. http://electronicshelponline.blogspot.com/
Pull up previous posts by its left sidebar, or type in the brand name and model number to of your set, to its search box, and press 'Enter' or view it in Mosaic / Timeslide option.

sounds like the sound board is not getting the proper power. would check the power board for worn out capacitors or leaking ones. cheap fix if you know how to use a soldering iron.

will it come back on if you wrap it on the side? Probably a bad solder connection on the circuit board

have the wires right in the back of the TV, or unplug everything and start over from the get go.

If your set all of a sudden won't come on, e.g., the screen is blank, but the LED on the under the screen next to the on/off switch keeps flashing, then there may be an internal fault on the set that needs to be reset.
To force the reset, try this:

• Unplug the set and wait a few seconds
• Replug and see if the video returns

Whenever the set senses an internal fault through its monitoring circuitry, it essentially shuts down the set. The flashing LED provides the indication that a fault has been detected. Removing power to the set resets the monitoring circuitry. When plugged back in, the circuitry again does a check of the system. If it finds that there truly is a problem, then the set is shut down and the LED will again flash. In this case, you need to call a service tech. Most of the time, however, the unplug/replug routine is enough to get the set up and running.