Shipping crate issue

Backgroud:
1.Recently,our customer received two units with the losen bolts on the crate.And the shock watch shows red.
2.The bolts are used to lock the units on the crate.The shock watch goes red if the crate was violent knocks.
Cause Analysis:
1.Checked the screws spc, found the nuts match our drawing,but the screw is small.So there will be a big clearance between the nut and the screw.It is easier loosen than normal.
2.There is no torque force spec for the bolts.
Contaiment Actions:
1.SQE contact with the supplier, change all the incorrect screws.Supplier applies the CAPA.
2.Engering team calculate the torque force for the bolt.And crate a deviation to support the change when the units start building next time.
Corrective actions:
1.A Enterprise change order is needed for the torque force.
Query:
1.Why the shock watch turned red?
First,The units were shipped by sea.
Second,the inside units may hit the crate.
I measured the dimensions of the crate,units,the clearance between the unit and the crate.Caluting the shift per assuming the unit can hit the crate,the shift is impossible in fact.
Summarize:
We should privide persuasive evidence when we can't make sure whether the defect was caused in the manufacture process or other related process.