It stays in safe mode, asks to reinstall the system, or hangs on the logo.
A failed update, a bad drive, or a power cut.
A system reinstall that keeps your saves when possible; a new drive if it has failed.
It depends on the model and on what we find inside, so we quote each repair individually. The diagnosis fee depends on the device, and you approve the exact repair price before any repair starts. If it can't be fixed, you only pay the diagnosis.