The back hatch won't unlock and release with the key, or manually. I just recently had the rear bumper repaired and painted.
The rear bumper cover removal and installation should not have been an issue, unless the rear sill plate was not installed correctly, which could jam the rear hatch and not allow it to open. The MDX latches are prone to rust. Once the plastic plug is removed from the interior for the manual opening, the latch assembly can be sprayed with a penetrating oil. This can free up the latch, and the rear hatch can be opened. You may want to enlist the help of a mechanic, such as one from YourMechanic, who can inspect your rear hatch not unlocking issue, assist with getting it open, and diagnosing the scope of repair necessary.
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