Iphone SE overheating

[George_Bud]

So... I got this Iphone SE... it was in good shape, the screen is good. But the last owner said to me that the battery discharges very fast and it overheats.

So.... I took out the battery and got a new one. Now the phone is over heating like crazy.

I have a USB Detector that shows V and A. It charges normal for a few second ( like ~5V and ~0.4 A ), but after a few second the USB Detector show all kinds of variables. ( like 0.01 all the way to 0.4 ).

 

What do you think may be the problem ? Should I try to disconnect everything and try with only the motherboard and see if that heats up ? 

Or is this a known problem ?

[George_Bud]

#### Update ####

 

It doesn't heat up if I only connect the mother board and battery.

 

Ok... So it must be some problem with the other parts, I guess....

 

[Bruno_A]

I can't explain the voltages, as I'm not an expert, however, I owned an iPhone 5, 6, 6S, 7 Plus, and now a XS Max, and, with my experience with all the previous models, but the XS Max, which is still relatively new, is that as iPhones get older, they start heating more and more, which affects battery life. I am not sure if it's a problem with the phones themselves, or the fact that I used Apple cases, which have fabric on them, and insulate the heat, basically wearing the battery even more, and potentially damaging the CPU. I may be completely wrong, but there could be a relation.

[George_Bud]

I connected everything else except the usb port thingy....

Now it doesn't heat up anymore but now I have another problem.

 

The screen is not working.

 

I know it worked. I've seen it. Maybe there is something wrong with the screen too.... Not sure yet. 

 

BTW.... The battery is new. So.... I think that is good. The battery has 3.86V.