Battery replacement for precision mechanics with electronics knowledge

Have this hair trimmer now about two years.
The cutting capacity has decreased somewhat in time. Is probably also related to the battery, which I wanted to change now.
Need to change the battery disassemble the whole unit is unfortunately.
It is not intended that the battery should be changed at this hair trimmer.
Thus, it is a disposable product that can be discarded after the lifetime of the battery.
If you do not have appropriate training (Elektrotechnischer invokes focusing precision engineering).
One need not even start the unit assemble apart.
What is needed is a soldering iron (80W), precision mechanics Screwdriver Set.
Working time is approximately 1.5 hours.
Therefore, there is only one star.
Incidentally, the battery will - power to specify with 800mAh. In reality, a battery with 730mAh is installed.
I am well aware that this is not a big difference, but we are talking about almost 10% deviation.

Therefore, the hair cutter is not recommended. Pay attention that the battery can be change.

Rather spend a little more money and then do not fret.
The hair trimmer costs at least 27 I basically want to invest every 2 years.
Thus, every month. 1