I was on the hunt for an air purifier and the Xiaomi 4 Pro caught my attention because it had all the features I was looking for. However, I was annoyed when the replace filter warning kept popping up even though I knew my filter had plenty of life left. I decided to dig deeper and discovered that someone had reverse engineered these filters and published their findings. They found that the NFC tag on the filter was locked and couldn’t be edited without a password. Luckily, the Proxmark community had already figured out how to crack the password. I explain the process in detail in this post. You can also reset your filter using your NFC-enabled smartphone. Overall, this information is valuable for those who want to save money and reduce waste by resetting their own filters.
https://unethical.info/2024/01/24/hacking-my-air-purifier/