OS Mega no boot flashing red light...help

[superboots]

My OS Mega will not boot and all it shows is a flashing red light.
I've turned off the power for a while to no effect.
Also tried to re flash but all I get on display is a red flashing light nothing else.
Power supply is supplying the correct voltage.
Manual is basic with no troubleshooting help so hope someone can help

[abu baniaz]

Correct voltage. What about amperage? Might be easier to check with another PSU.

[superboots]

Now tested with a known good power supply and still just a flashing/blinking red light

[Sicilian]

Disconnect everything apart from HDMI. Disconnect and internal HDD cables, feeds etc.. Just leave HDMI and try again.