iPad'1110'Cannot power on, extraction failed

I was assigned to a technical consultant at an Apple Store to assist with a system upgrade. Before the upgrade, she merely inquired if I had backed up my data and then proceeded with the upgrade, which led to my iPad being unable to power on and getting stuck at the upgrade interface. I believe her operation was unprofessional. She did not check the remaining storage space and memory on the iPad before performing the upgrade and signing the "Risk Acknowledgement". She also did not assess and inform me about whether the remaining storage space is sufficient for the upgrade, whether it is enough for the update package to decompress, and whether having too many apps might affect the system update. There was no assessment or notification given before the upgrade. This is a fundamental prerequisite and is necessary for any software update process. After subsequent contact with Apple's official technical support, I was informed that it is impossible to restore. I am seeking help here, hoping that someone can inform me if it is really impossible to recover the data?