Problems with ZTE axon Pro

I bought my ZTE axon Pro a year ago and it worked fine until a few days ago when it started charging slowly with an original charger, also I have an otg flash drive and it doesn't recognize it anymore furthermore I powered off my phone and I couldn't turn it on until a few hours later and somehow the battery drained even though it was on 40% when I turned it off
Well I can't pin point the problem I would appreciate the help

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