Acer Chromebook: blown motherboard component?

It’s hard to tell from the picture. A blown motherboard component would have probably made a noise and emitted some kind of smell when it detonated. Also, the computer would have likely become symptomatic immediately.

It could be a blown component, or that white mark could be because of a manufacturing defect. Perhaps the unit is refurbished, or was otherwise handled by a technician who damaged it?

To make sure that the power port is at fault, I would probably first replace the battery and see if that doesn’t fix the issue. It’s always best practice to try the least invasive solutions first.