I just bought a Bianca player from Uxcell and it was restarting with the hourglass. At first I thought it was static doing it but the whole case is plastic and non conductive.
I opened it up and checked it out for bad connections but it is damn tight in there and nothing was disconnected except for a battery lead that was never attached in the first place. After screwing around with it for a few minutes I noticed it worked out of the case but had the same problems when I put it back in. Well it comes to be a piece of tape was put off center to the speaker that had a metal backing. So I put a piece of tape on the back of the speaker over the metal and it fixed all the problems.
BTW I noticed the player has a Li-Ion Polymer battery built in.