You take this little to the mobile phone store to press a back cover for a few tens of dollars, the new model may be about 100 or so, even the machine does not need to be dismantled, but you may lose the official warranty eligibility (not sure whether it will break the warranty rules in the case of no dismantling)
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If you take it to the official to replace the rear glass, I just checked that the repair cost without ac is 3109.