My Problem
Freezing with Kernel Panic directly after startup or working for a while.
Apple Store => Logic Board Problem
=> No more guarantee => ca. 370€ repair costs
My Fix
Apple Hardware Test showed Memory Error on Logic Board
=> Bought a used working Logic Board for around 250€
Repair with iFixit Tools in about 30min without any problems
MacBook Air works like new again
My Advice
Take your time
Follow directly the iFixit guides
Use the correct and especially good tools
Written