Xbox One won't power on after disassembly & clean - damaged RF board?

Hello, first question here but long time lurker and repairer (semi-professionally for a time too).

So my house mate upgraded his Xbox One and decided to put his old one in our living/common area as a media center. He’s had it since launch and we lived on the beach for a couple years so I thought it a good idea to disassemble and inspect for any corrosion, clean dust and so on.

To my surprise the console was pretty clean inside, just the usual dust buildup on vents, heat sink and fan blades. No problems here - I cleaned it all with a battery-powered air gun on lowest setting, and the fan blades with alcohol and toothbrush.

Upon reassembling however, I accidentally (shame) tore the ribbon cable for the front soft buttons to the RF board. Whoops. No problem, the controller can turn it on until a replacement arrives - but the controller did not. I guessed this was because another controller had been paired to the console since, despite this controller still working on it before I originally disassembled.

I traced the pin-out for the front soft buttons so I can manually short it to get it going - pins 1 and 2 on J3 are for the power button. This worked at first, kind of. It powered on only half the time, but almost every time it would instantly power off or make the double ding sound when you try to eject with no disc. When it would stay on, that double-ding eject would randomly play sometimes too every few seconds, and even while the device was off! It seemed obvious to me that there was a short or failure on the RF board. But I could still get the console started and onto the UI some of the time.

At this point my housemate informed me that sometimes the device would randomly power-on by itself when he wasn’t there too, and I recalled this happening late at night sometimes too - at the time I thought he might have had some setting to wake itself up for updates though (if that’s even a thing for XB1).

Anyway, I decided to give the RF board a gentle clean with alcohol and a soft toothbrush.

After letting it air-out for a few hours and reconnecting everything, I can now no longer get the console to power on *at all*. The only sign of life is that I can hear some minor electrical noise (possibly coil whine) while it’s plugged in, somewhere between the HDD and APU.

The power supply is not faulty - the light is/was always a solid orange or white - but I don’t have another one to try to be sure on that.

So, on to my actual questions:

1) Has anybody experienced this before? Can the RF board die like this, completely preventing power on?

2) I found that there are some bare headers underneath the optical drive - Power, Warm, Cold, and Eject - however the Power and Eject do not do anything when I short them. Are they actually connected to anything (i.e. do they work for anyone else)?

3) Is the RF board required at all for the device to power on? I am thinking that RF board damage could be preventing a power-on, but if removing it completely will still prevent it from starting at all then that’s obviously not useful.

4) Is the Wifi board (or whatever it is - the one on top of the metal lid) required to be connected at all for the device to power on? I’m not sure if leaving the console all open and half disassembled (metal lid removed) on my bench is fine or not.

I’m worried that I’ve somehow destroyed the motherboard, despite me being very careful with it. A replacement RF board is relatively inexpensive, but I need to import from Hong Kong so I thought I’d ask for advice in the interim.

Thanks in advance!