The answer from Payam Toloo, Owner of Payam Data Recovery:
The boot loop issue commonly arises when storage capacity is full. If you have been receiving “iPhone running out of storage” notifications and consistently dismissed them, your phone eventually ran out of space, resulting in a boot loop. This is the typical cause.
We possess specialized software to safely back up all your data, including photos, videos, and messages. There is a strong likelihood we can assist you. In rare instances, the issue may stem from a hardware problem, such as damage to an electronic component within the phone. We can diagnose and rectify such problems, then proceed with the data backup without issue.
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