I would consider doing a screen replacement. New screens are a bit costly though

I would clean the contacts (the gold parts on the bottom) with a cotton swab that has isopropyl alcohol on it. It might work.

there are a variety of reasons for this to happen. If you have had this phone for a minute now, it could be the charging port, but I would check the charger you use first. If it has died quicker that what it used too, it could be a battery issue. If none of these being replaced work, I would take it in for a repair.