Tmo employee here. When you purchased the T-Mobile variant from Samsung directly, Samsung locked the device but failed to provide us with the IMEI. Message our Twitter team and let us know that you purchased a TMO device from Samsung, provide the IMEI and a photo of the receipt, we will have it unlocked in 48 hours.
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All android versions since 9.0 automatically wipes the cache when updating. This is why you see the "optimizing apps" screen upon the first boot..
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