There is basically no technical way on the mobile phone, in addition to the universal wifi key you can try, and you can see the password with the two-dimensional code shared by the Xiaomi mobile phone.
The computer side can use the water drop or baby bottle under cdlinux to try (there are many tutorials, but only some network cards support this operation, such as Realtek 8187L).
If you use the dictionary brute force cracking, the general process is relatively long, depending on the quality of the dictionary, may not be broken.
If the router opens wps, you can try to break the pin code, eight digits, relatively easy, not necessarily long, but certainly can break.
Before the Android end is also broken pin code software, but now can be down to most of the fake.
The water droplets and bottles under cdlinux are relatively shallow operations, and people with computer foundation can follow the tutorial.