I dropped my Xiaomi Note 4 and badly smashed the screen. Took it to "Mobile Repair Pro-Shop," Unit GB81B, Sin Tat Plaza, 83 Argyle St., Mongkok (ph 9839 0831). Replaced screen parts + labor for HK$400. Took about 40 minutes. Xiaomi (HK) wanted to charge HK$1,200 to fix, the phone only cost HK$1,500 new!!!
There are many other mobile phone repair shops in this building so hard to choose which one to go to, I picked these guys because of previous good reviews and they speak good English.