When you measure the resistance between 5v and gnd, on a place where is an IC, basically the ic may see a sort of supply and some parts of the ic can get more or less activated. So the results are probably not going to be stable and not very relevant, but at least should be in some reasonable interval.
The 5v is logic supply, so generally this consumption is very low in few mA range. A driver could draw like 5-10-20mA, and atmega could draw like 100mA, more or less around that. But the 10-40 ohms range is not reasonable, because if a driver tries to draw 5v/10ohm = 0.5A at 5v, that certainly is a problem. While their 5v-gnd measurement seems ok, it means there is some other point they draw 5v from.
Try measure between ground and each of the points MS1, MS2, MS3, Sleep, Reset. These are also tied to 5v, so perhaps the short goes through one of them. Perhaps that should help identify the problem driver.
The 5v is logic supply, so generally this consumption is very low in few mA range. A driver could draw like 5-10-20mA, and atmega could draw like 100mA, more or less around that. But the 10-40 ohms range is not reasonable, because if a driver tries to draw 5v/10ohm = 0.5A at 5v, that certainly is a problem. While their 5v-gnd measurement seems ok, it means there is some other point they draw 5v from.
Try measure between ground and each of the points MS1, MS2, MS3, Sleep, Reset. These are also tied to 5v, so perhaps the short goes through one of them. Perhaps that should help identify the problem driver.