Mid print it just stopped - wouldn't come back on.

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The plug is burnt and the receptacle looks corroded.
I know I need a new receptacle and power cord.
I saw an older thread about this and the advice was to test the motherboard. I'm not an electronics person so I have no idea about that. I looked on Amazon for motherboard testers and nothing looked like anything I know how to use. Should I just buy another motherboard?

What about the power supply box? At first I thought that would have to be replaced, but now I'm not sure. The light on the switch comes on when I turn it on, but nothing else does.

Last question - if I end up replacing these parts is there something that I can do - as an electronics illiterate - to improve the function or durablity of my machine or should I just replace them with the same thing? Sometimes I feel like I spend more time working on the machine than I do printing on it - I wouldn't mind an upgrade.

Any information or advice is appreciated.
Donna