The Baltic Sea USO - what's going on?

That's Unidentified Seabed Object, just to be clear. So I've been following the earlier Daily Mail articles about this strange rock formation on the bed of the Baltic, thinking "yeah, yeah, Face on Mars territory." Except that now it seems that there's an additional wrinkle:

Professional diver Stefan Hogerborn, part of the Ocean X team which is exploring the anomaly, said some of the team's cameras and the team's satellite phone would refuse to work when directly above the object, and would only work once they had sailed away.
He is quoted as saying: 'Anything electric out there - and the satellite phone as well - stopped working when we were above the object.

Now, let me say that my immediate working hypothesis is that Stefan is enjoying screwing around with credulous journalists. However, just supposing that he's reporting the actual facts, what's going on?

I think the most likely explanation involves the Soviet Navy; there's a long history of Cold War submarine activity with seabed-crawling Soviet mini-submarines, and the Swedish Navy depth-charging them. Maybe, just maybe this artefact is the result of some mid-1980s activity that buried Soviet (nuclear?) hardware under rocks and sand, broadcasting a significant RF signal for some as yet unknown purpose. The Russians are unlikely to admit any involvement unless actually confronted with the retrieved device.

Or maybe aliens crashed their spaceship into the sea, and this expedition will retrieve it. I've seen the second X-Files movie, and know that this never turns out well. Time to go short of Sweden?