Last week it happened. I experienced difficulties while trying to update operating system. It just did not load the updated version. Although phone functioned well until last Monday. After that it just did not boot up at all. Only Jolla logo was showing up. Even removing of the battery did not make any positive effect to the situation.
Finally on Thursday I delivered the phone to maintenance. Positive surprise was that they managed to fix the problem already on Friday. Now looking forward to pick it up next week to see what is left of installed software and data. Most probably nothing, but if you are pessimistic enough you will newer get disappointments:)
Now phone should be equipped with newest version of Sailfish, so next thing for me is to figure out how it has developed in relation to utilization of Android applications and application stores.