Usually a strip down and a can of compressed air… try and google fan cleaning on NUC 7i7BNH
https://communities.intel.com/thread/114068
The idea is to blow out the dust from the fan and also the cooling fins of the Heatsinks on the cpu…try not to spin the fan a million rpm when doing do, a quick spin is ok but remember the bearings are not designed to spin at turbo speed that the compressed air can achieve.
Might help for the disassembly part while not the same model the principal is similar