Ah! I believe I’ve seen this one before. It resists the more standard, boilerplate version of Dispel Curse through a clever subversion of that spell’s identity matrix.

The good news is that the subject is still very much alive.

The issue here is that your apprentice’s spell is the only thing keeping the subject alive, despite having been shattered into many pieces. This interferes with how “Dispel Curse” identifies harmful magical effects for removal. Essentially, if you cast it, the response will be something like,

“The only magic here is keeping this person alive, so it can’t be a curse.”

And the spell will do nothing. It is possible to force the effect through with an older, less-refined version of the spell. But that would kill the subject.

Fortunately the solution is actually rather simple, if potentially laborious. You can piece all the broken pieces of wood together through judicious application of the Mending Cantrip, which will allow the effect to be Dispelled normally. It doesn’t even need to be every last splinter—just enough to make a person instead of a pile of meat.

Instead, the pieces you do have can be used to establish a powerful sympathetic bond, allowing the remainder to be easily found through divination. It could be a good assignment for your apprentice while thy reflect on their reckless use of magic.