Before diving into downloads, diagnose whether your issue is software-related. You likely need new if:
The safest route is always the manufacturer. Lenovo doesn't always publicly host all its older firmware, but you can try their official support forums and knowledge base. Reputable firmware websites often host "stock ROMs," which are the original, unmodified system images provided by Lenovo. Tb-x605m Firmware
If you are stuck on a specific step, please provide the following details so I can assist you further: you see? Are you using QFIL or Lenovo RSA ? Before diving into downloads, diagnose whether your issue