First Alert Model P1210 Smoke Detector - Product Failure Review

Product Review of First Alert Model P1210 Smoke Detector, with 10 year battery.
To stop the beeping:
THE TEST BUTTON WILL TEMPORARILY SILENCE THE DEVICE.
For more information, the product manual is online here:
www.firstalert...
I purchased this in October of 2015. It failed on February 7, 2019. From its manufacture date, It lasted 1,274 days until it failed; it was supposed to last ten years, or 3,650 days. In practice, it failed after less than 35% of its expected life.
Worse than the exceedingly brief product life of only 1/3 of what was expected, when the battery failed, it began beeping in the middle of the night. Initial attempts to silence it were futile, because the device would not come apart to reveal any written instructions. Even after locating the complete owner's manual online, it was impossible to disassemble without actually tearing it apart, effectively destroying it.
For an unknown reason, this unit had fused to its mounting bracket. Instructions were hidden by the mounting bracket, although luckily, the model number was partially visible through holes in the bracket.
Instructions for separating it from the mounting bracket were nonexistent in any visible place on the device itself. Instructions in the owner's materials are vague or misleading. There is no clear way to identify how, if it is fused to its mount, how the device can be taken apart. I injured myself trying to dismantle it.
Technically, it should simply and easily snap open. Ultimately, after fiddling with it for over an hour, I could only break it apart in order to reach the switch to actually turn it off.
Note that if the battery fails as this one did, the manufacturer recommends that the device be replaced anyway, since it is not designed for battery replacement.
Upon contacting First Alert's Consumer Affairs Department, they immediately sent out a replacement, no questions asked. Their number is: 1-800-323-9005.