If your IMEI is "invalid" or missing due to a software glitch, you may be able to restore it without specialized hardware:

For the XT2083-4, if the IMEI is showing as "Null" due to software corruption, the only legal repair method is flashing a backup of the NV data if the user previously made one. If no backup exists, the device is essentially a WiFi-only tablet, as writing a new IMEI is illegal and violates Motorola's security protocols.

If the issue started after an OTA update, a full reset from the recovery menu may recalibrate the modem partition.