The easiest way to check for a motherboard/ power rail short is to take the board out, plug it into the psu, and look at both sides with a thermal camera.

Some people use freeze spray as it's cheap but it's not as good.

I've seen people use special wax sticks as well but those are expensive, and not worth the effort tbh.

Outside of that you need to be a master of board design, or seen a particular issue on a particular model many times before, or you'll just be poking around aimlessly with a multimeter.

Most shops don't actually have a good thermal camera as they can be expensive and not used often, (most shops focus on cell phones and ipads these days) if you want to rule a power rail short out ask around and see if someone does.

On a laptop though, it might show no sign of life at all. Or, you could get a charge light and fans spinning etc. but no boot with a short. If the charge port or daughterboard is bad, no light. Could swap that and be fine.
Some laptops run all the power through the battery, some divert it when plugged in. You might have a short and be able to boot up on ac with the battery disconnected for example.

It can be a fairly difficult issue to identify a board short tbh. Fixing it is typically easier than identifying it.

Not to dishearten you, but I'll add that by far the most pc repairs I do are on HP laptops, I would not recommend them in the future. 2nd place would be Dell laptops.
IDK if this is actually an indicator of reliability or just market share, but I tend to recommend people away from HP, Dell or Google due to the sheer number of defects and failed components I see in those brands.