I have a lg lmv
if it does not power up, then it means its having a power problem. it might have worked fine in the past, but that's electronics for you. Power surge, irregular power supply, excess power supply, etc can affect the unit thereby not making it to power on.
This unit must have a power supply board in it where power enters from the mains. A capacitor, fuse, diode, etc may have been defective on the power board and maybe that's why its not making the unit turn on. There might also be some disconnection or something, inside the unit which is not making it to power on.
To actually find out what's wrong, you need to disassemble the unit with a screw driver and check what's wrong. You will be needing a meter in order to test the components on the power board, once you detect any bad component, you can make necessary replacement at any electronics accessories store withing our vicinity. This is the only way by which you can detect the problem.
Of course, testing the power board with a meter will require someone that has the ability. So it you can't, then you might be needing the help of a repairman or you can call a friend that has the ability to help you out.
I wish you the best of luck.