touch screen cracked of its own

initially a pale yellow spot appeared on left side of the screen....

after two days my touch screen got cracked of its own..

i have been using mi4 from more than one and half years without any complaints,

tempered glass was also there..

there were less cracks on tempered glass than phone...

i didnt understand what has happened......

can anyone tell me about how to get it fixed from authorized xiaomi service centre...