Ambition mods k1 USB problem

Ambition mods k1 USB problem - Ambition Mod 60W chip
When the fire button is activated, the negative contact of the USB connector heats up.
With long puffs, the lower part of the mod heats up and I even got small burns on my little finger several times.
In this regard, I decided to unsolder the charging board.
Results after the manipulations performed:
The resistance stopped jumping.
The battery charge now lasts one and a half or two times longer with my builds.
Now I am not afraid of getting burned 🧐.