Abnormal Battery behavior iPhone 5

Hi guys,

I am using an iPhone 5 as my spare phone. One day, I noticed that the battery was draining very quickly and cannot hold the charge. Hence, I ordered a new battery to replace it. The new one worked better, but still drained very fast and fully dead after 12 hours without me using it at all. I observed a few abnormal things:

• After fully drained, I plugged in the charging cable. The phone awoke, the battery showed ~ 14% and it would slowly decrease to 0% (although there was 1A current flowing in, see attached videos), shut off, show the battery charging icon and after a while, boot up again. Then it would charge normally to 100%.
• I used a software to look for the battery info. However, the software showed that the number of charge times is 0 although I have charged it 10+ times.

Can anyone diagnose the issue please? Thanks!