2014 MBP won't boot, makes ticking noise

TL;DR mac won't boot, makes ticking noise (though no hard disk that would click). Maybe it's shorting out?

Yesterday, out of the blue, my laptop was off and would not boot, making a ticking noise 1/sec. If the mouse is plugged in, the mouse light blinks in sync with the ticks. When I unplug the power cord, all ticking stops.

I called Apple Customer Support, and a System Management Controller reset solved the problem... or so I thought. I used the computer just fine for the day, and the same problem appeared again when I left to the bathroom, SMC reset worked again.

That evening, however, I decided to install the new update (thinking that could fix the problem), and the behaviour of the problem changed. Now, it only ticks while I hold the power button, and SMC reset is ineffectual. If I unplug the computer, it has about 5 ticks before it stops ticking.

This was a refurbished model, had slight manufacturing defects from the beginning (doesn't output video over thunderbolt, one USB port is shorted), so my best guess is that two parts that shouldn't touch, are. I dropped the laptop once, on the corner, but that has not caused any issues. I spilled water on it once, immediately shut it down, then allowed over a week for it to dry.

I can't fathom what the problem could be, as my computer does not have parts that move. Here are the specs as I remember them:

2880x1900 Retina display

Intel i7 CPU

Intel 4000 GPU

250GB SSD

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