That is a huge problem honestly, I don't know how these repair services handle this thing when it comes to Bitmain's 17 series, these gears are of very low quality, it will be hard to offer any sort of warranty given that fact that another chip might just fall/burn in just a few hours post-repair, they could tell you that if the same chip which they repaired fails again they will fix it for free but then who will handle the shipping cost and all the other expenses?

As they say "The devil is in the detail", and therefore, before shipping any gear for repair one must ask all these questions.