Aberrant completions measures after just 3 uses

I bought this cheap multimeter, at fair basis for testing rechargeable battery and possibly occasional electrical measurements.
At the beginning, no problem; after then wanted to test the conductivity of a lamp 1 ½ months after my purchase, it will indicate ... nothing. I then tested the electrical outlet, and I had the right to inconsistent values ​​ranging from -180 to -65 V (instead of + 230V), while I was set on AC right caliber and such a current can have negative measures. Then in testing all other calibers without making contact with anything, I get a negative value around 20 V ... And whatever the mode (voltmeter, ammeter, ohmmeter ... ), I get there too vacuum illogical values.
It must surely be a short circuit inside, systematically distorting any action ... I am extremely disappointed after only 3 uses, and of course 30 days withdrawal Amazon expired two weeks after the crash. Because of the low price of purpose, a return to my office is not worth the shot. I had to fall on a bad camera ...

Otherwise, a plus for the 9V battery included, but at least for the class selector where it is difficult to distinguish which side is the selection arrow.