Cannot activate my Iphone X after reset

Hi, I initially had an error on my phone "Cellular update Failed. Your iphone cannot make and receive calls or access cellular data until it has been updated." Following the guides and articles I found (apple site and other users), I tried updating the network setting, removed and put back the sim card, updating the phone using my Mac. When updating the phone using mac, it did flag that the update was successful but when I checked the phone, the same error persisted. Last resort is to reset the settings to factory default (which normally works on any iphone) and just set it up as a new one so I did. Unfortunately after reset,I no longer cannot activate the phone. Error encounterd is now "Unable to Activate. An update is required to activate your iPhone.". Anyone hear has the same issue before? Were you able to fix it? If so, can you let me know how? Thanks!