Screen not turning on but touch is working

So long story short after 1 yr of own in 2017 the battery basically puffed up causing the back to crack... changed the battery by samsung (not under warranty), and worked fine until a year later in 2018 it again expanded but not crack te back glass but raising the screen got that fixed again not under warranty. All happy and not able to afford a phone as a highschool student (phone fixed and passed on by parents) now agian a year later battery is puffing a little but not alot so trying to work with it but the battery is not holding charge for even 3 hrs and the screen sometimes doesnot work and sometimes when turning on it has green and pink flicker (flicker stays on for a second) but wont show anything but the touch is working is i can hear the phone unlocking tone and when open yt cuz i know its on the home screen the video can be heard but not seen confirming that the touch and the phone is working but not the screen

Help me please from where i am highschoolers dont get any jobs and the payscale is pretty low as i am in Pakistan a good phone with okish specs cost like 20000rs which is bout 200$ish and cant afford it