XXX: Completely expected behavior. Purchased a Chinese soldering station - open and:
1) Eliminate all suspicious places
2) if the section of power wires is insufficient - replace with thicker wires
3) look at and, if necessary, change the radiators on power cells.
4) if necessary, disconnect the filtering and protection elements instead of switches to the placed place
5) look at the scheme and add what is necessary.
It looks like buying a domestic car.