Grading system
Functional Grade
A : fully tested
B : small problem ( button , sound , charging , face ID)
C : board damage partially
D : board damage seriously
A+ : clean and battery 90 and up
A: no need housing change , no need polishing or glass change
B + : no need housing change , need polishing only ( good LCD)
B : no need housing change , need glass change ( good LCD )
C : Require housing change (with or without glass change) but good LCD
D : serious crashed with bad LCD