Hi everyone, problem solved.
This issue maybe triggered by the Thinkpad 's whitelist. Maybe thinkpad bios block the access to module after firmware updata failure. So I can’t see any device under device manager when I insert the module to M.2 WWAN solt on x270’s motherboard.
So I bought a USB TO M.2 WWAN adapter. As expected, EM7455 is visible through USB port. I can see port device in DM, and I can rewrite the firmware. When the firemware back to normal, it’s also visible in x270’s M.2 solt.
Hope this topic is helpful to anyone like me:)