Lenovo uses whitelisting in the BIOS system, your issue is the VEN-ID with the card, not the IMEI…
I changed one from Dell’s code to the generic one a long time ago, but it is risky (can brick the card). I wouldn’t know what to enter for what Lenovo wants. Is the EM7355 an option for Lenovo for that laptop, if it works in your X1…
Alright… I looked it up… Your title has 7455, your post has 7355… The 7355 will not work in the Lenovo P50. A Lenovo 7455, likely. 00JT542, will, this is the part you need.
This is just Lenovo being ‘special’, many of HPs laptops have similar issues too… You need their parts, and only their parts. You won’t be able to change the WiFi card either by the way.