To begin with, I was very careless and reckless in opening and attempting to repair my hard drive from home with little knowledge of how fragile they are, and how complicated the process is.
Fortunately, Dataclinic was able to recover virtually all of my files.
During the process, they kept me informed of the status of my unit, and they answered clearly all my questions and doubts.
It should be mentioned that the service is not "cheap" at all. I am not aware of the prices of other recovery centers, but the quote I received was within expectations based on prices found online.
Data recovery is a highly specialized process, using expensive tools and processes that not just any local or professional technician can have, so one should always expect to pay much more than a new unit would cost. However, the money can be recovered. No data, much less if you don't have backups.
The final verdict is this: Always back up your data to one or multiple outdoor drives (or to the cloud) to prevent these types of incidents, and NEVER attempt to repair or even open your hard drive. Just exposing it to the open air can cause irreversible damage and make it much more expensive to recover the data, as it was in my case.
That being said, I am satisfied and very grateful for the service provided to me, and I can recommend Dataclinic for data recovery.