You may find your iPhone XS Max will not get past a screen that says "Unable to Activate - An update is required to activate your iPhone". You may have noticed that your cellular service was not working properly and attempted to update or restore the phone to fix the problem, and then became stuck here. If so, then you most likely have a motherboard interposer (or sandwich) problem. It is a trend of these newer model iPhones with stacked motherboards for disconnects with the interposer to occur. When this happens, the voltage lines across the two motherboards are severed and cause problems.
This is the problem that you will see:
If you go back to the beginning, you will see this icon. Press the "i" to verify the problem:
If the only information you see is the Serial Number, then the baseband circuit is missing voltage lines, typical of a bottom board partial disconnect:
This is fixed by reballing or even reflowing the interposer. When this is done properly, you will see that you now have the information that was previously missing:
Once you have your bottom board properly connected to the top and all voltages flowing smoothly, you will be able to input your iCloud information and continue to use the phone:
If you run into this problem and need to have it fixed, please navigate to the request a quote page. Thank you!