Computer doesn't boot and blinks a blue light

Hi guys!

I picked this thing up from a friend today to repair. He said it wouldn't turn on. Figuring it would be a simple fix, I accepted. On each side of the machine there is a USB-C port. When I plug power into the right port, nothing happens. However, when I plug power into the left port, a blue light on the right side next to the USB-C port starts blinking. When it does this, pushing the power button does't do anything. I have tried various combinations of holding down the power button, to no avail. On some power adapters, it will only blink a couple of times before stopping. I have also tried disconnecting the battery and plugging it in + pushing the power button. In case you were wondering, I have also tested the power button for continuity, and it functions as expected. Although both USB-C are on daughterboards, I have double-checked that both connections are snug, as well as disconnecting and reconnecting both of them. My friend said at one point, the machine had been dropped with something in the right USB-C port, and said after the drop, the port had never worked. However, he said that the machine continued to function for a few months afterwards before dying. He could not remember any details about when it died, as it happened a few years ago. I'm thinking the problem is the motherboard, but I'm no expert, so I wanted to get a second opinion before carrying out such a repair. I can attach pictures, if necessary.

Thank you very much!

EDIT: Attached images: