shop

Hallo, for half a year i bough the mi max 3 and now it dont starts anymore the mi logo show up and and it crashed i remeber the last what it shows was "miui cant install". I was allready in an phone repair shop but they cant help me they mean somethink is with the motherboard. I had try myself...

I'm posting this cause I haven't found any FAQ page, and if it exists it's probably not very visible... Basically I wanted to know what are the options. Which shops are the most trusted/cheap/reliable?