M48Z02 SRAM unexpected data loss
Is possible that the battery failed and data were corrupted?


Yes, it is possible. Are you following the procedure in the datasheet to check for low battery voltage? Depending on your source for these ICs (e.g. official or not), the chances of battery problems changes, in my experience.

However, your description may point in a different direction:


  About 5 hours ago I've programmed my SRAM and than inserted it into the stripboard manager. Now, when I wake it up it shows wrong data in some addresses.


So you've been powering-on/off the ICs.  Notice that on page 12 of the datasheet, they discuss a specific situation which can result in data corruption:







Notice specifically the part which says: "These negative spikes can cause data corruption in the SRAM while in battery backup mode."

Therefore I suggest you follow their recommendation for a Schottky diode and decoupling capacitor as shown in the datasheet, and re-test.