I have a weird problem.

@mikolajiwanicki couple of things you want to do first. No, you so not yet have to go to a repair service. WE support self repair and always try to give you options to repair it yourself. First thing to do is to replace your battery Xiaomi Poco M3 Vervanging van de batterij and your charging board. Since iFixit does not yet have a guide for that, use the one from here It is in spanish so use a browser that supports translation. Those parts are relatively inexpensive and easily obtainable from many online sites. While you are working on your phone and you mentioned you have a cracked screen, rpalce that at the sem time Xiaomi Poco M3 Vervanging van het scherm