For Qualcomm device you cannot READ CERT but can only WRITE CERT from who have one from his device and Share it, (obvius not in same country/operator itc..), or from any server that will seller these.
You not damage you device if CERT is good,
FIRST MUST NEED OF CANCEL ORIGINAL CERT, the only mode for do it is Wiping EFS and after WRITE new one.
For Exinos devices You can READ/WRITE CERT.
FOR QUALCOMM, YOU CAN WRITE CERT FROM OTHER N900 to OTHER N900X IF THIS HAVE “CERT” WITH FULL UNLOCKED AND IMEI/NETWORK OK!!!