Envy 4-1117nr

How To Update Mavericks 10.9.2 Without Losing en0 built-in on Envy 4 i5-3317u

After updated to Mavericks 10.9.2 from 10.9.x, we may lose the en0 – Ethernet built-in which causes iCloud, iMessage, Facetime and Apps Store NOT working. To prepare for this not to happen, this is the way I did my update successfully without losing the Ethernet EN0 settings by the new 10.9.2.