GE JVM1870SK03 vent fan, turntable and lights are out, seems to still heat food but sounds funny
Hello, welcome to Fixya!
The unit not powering on is an indication that it has a power fault.
First, remove the microwave's power cord from the wall, wait for about 30mins, then plug it back in. It may cool by then and might power on. If it doesn't power on, plug it into another outlet, to make sure there electricity entering into the unit.
If plugging into another power outlet doesn't power it on then the unit is most likely having a power problem.
When electric current comes from the power outlet into the microwave, it goes straight into the power supply board which then circulates the current into the unit. So if the microwave doesn't power on, the first thing is to make sure there is power entering into the machine.
So check the power cord, if it is a 3-pin plug, it must have a fuse in it. check the fuse if it is not blown. if fuse is intact, then power supply board should be checked.
If any machine or electronics device doesn't power on, 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 microwave 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 microwave 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 and continuity tester in order to read the components on the power board, once you detect any bad component, you can make necessary replacement at any electronics accessories store within our vicinity.You might also find visible bad component without testing with a meter. 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.