When liquid is accidentally spilled on electronics, it is often recommended to power down and disconnect all power as quickly as possible without causing further damage.
Then let it dry completely, eventhough it can be hard to wait, let it dry out completely.
Avoid doing too much troubleshooting while the liquid still hasn't dried out, and could potentially cause further damage
Once dry, you can power on and try and see what damage might have been caused.
The powerbutton on the front panel is very basic and is not complicated like a phone or a laptop.
Personally I think the power button will return to normal function, once it has dried out. This is my personal opinion, Iam not an electronics engineer, but liquid spilled on the front panel swith, is usually not catastrophic - but if it is a large amnount of liquid, the problem will have more potential to cause damage of course - but I don't hink I've ever seen vape juice being sold by the gallon privately, so my guess is that it is only a small amount
You could disconnect the power button from the motherboard for a few days while it dries out, and manually short the PWR_SW pins on the motherboard with a screwdriver to power on, until the switch is functional again (while being careful of course)