What is the method for weighing a male newborn's hair after shaving it on the seventh day, and should the shaving be done with a razor or clippers, and is there any consequence for not shaving it?

Shaving the newborn's hair and donating its weight in silver on the seventh day is a Sunnah, not an obligation. The hair can be removed by any method. The weight of the hair can be determined by placing it on a scale, or by estimating its weight without a scale, and then donating the equivalent. There is no blame on someone who does not shave their newborn's hair because it is a Sunnah.