Hey there. I kinda screw up here.. I wanted to install magisk on my (rooted) phone. I own a Huawei P9. In an online tutorial it said that i had to uninstall SuperSU so i did. After uninstalling i could not start up my phone. All i could do was entering the recovery mode (in this case twrp launcher). And from there i accedently unistalled my OS... I have no backup of the phoe or anyhing... Is it possible to fix this by my self or do i have to pay some professionals do their work?