What is wrong with my samsung galaxy a50 ?

My phone wouldn't turn on or charge . I recently took it to someone for repairs and they said it was the motherboard or the charging board . 1 hour and a half later it looked like it was fixed , it turned on . So after like an hour it ran out of battery and I connected it to different chargers because 1 wouldn't work .. out of 4 chargers I tried with , phone still wouldn't turn on . I went next day and they said it could possibly be the display , but I think it's not that because when they fixed it the display was working fine .. idk why they told me it might be the display when I went to go pick up my phone . They should've already know everything wrong with it the 1st time I took it to then .. so can anyone tell me what might be wrong , could it be the display like the person said ? And i don't think it's the charger .. tried with 4 and wouldn't turn on 🙁