From your symptoms, I strongly suspect the power supply boad.
The supply will have a 5 volt standby circuit that's always on (e.g. 24x7, lights the led and responds to the power on switch, front panel/remote, which will then turn on additiona power circuits).
The remaining circuits are at least 5 volts for the main logic, 12 volts for the audio and black light inverter (some sets also have a 4th circuit of 16-18 volts).
Since you have a voltmeter, check the output voltages (the voltage will be silk screened on the board at each of the output connectors).
Fixed a Dynex this summer that had a blown $50 cent pico fuse (looks like a resistor) on the circuit that supplied the audio and inverter voltage. However, a failed voltage output could be any component in that part of the supply (a semiconductor, resistor, capacitor etc.).
If you can verify the power supply board is the culprit, they are pretty easy to change out and you should be able to find a replacement board for +/- $50.