Please follow the below steps:
1. First confirm whether the SIM card has opened GPRS traffic.
2. See whether the network signal of your environment is normal.
3. Change a SIM card to see if you can download MMS and eliminate the reason for the SIM card.
4. After trying the above, if the MMS cannot be downloaded, try restoring to factory settings after backing up important data.
If the issue persists, contact the Nothing Support Team for further assistance.