pls my phone recently stops charging while on, it only does that when it is switched off. Techno S9, it does not connect to computer even after I've enabled USB debugging! pls someone should help me out! thanks in advance

lemme quickly borrow ds space


Hello gurus, my tecno phantom pad N9 is really giving me a lot of headache now wt its battery inconsistencies, I bought it a year ago nd I've been battling ds issue for a few weeks now.
I may charge for more dn 8 hrs yet it won't reach 100℅, in fact d % may just increase by say 5% after hours of charging.
I believe it might be calibration problem so I exhausted d battery to zero level nd then charge but it hardly reach 100% after several hours of charge. Even in occasional situations where it reaches 100%, I might switch it on to see like 10% nd d battery then depletes nd phone goees off within about 30 minutes of use. In fact it even continues depleting while being charged again.
At times I see 0% on switching d tab on after I've charged it when switched off.
Also, at occasional times when it charges to 100% while being charged switched on, d transition time is always very short, imagine reaching 100% from 10% within 10 minutes, however when I unplug, d battery depletes from 100% to zero fast within like 20 minutes, OMG!!
Then, if its switched off nd is charged, it can't be switched on if removed from power source, it requires being connected to power source to switch on.
All this problem actually started after I used power bank for about 3 weeks with it wen I travelled to a town wt poor power supply though I inquired prior nd I was assured dt d phantom-A power bank won't harm my battery, now see me see trouble o.
HELP PLS!