If your bios is getting reset it's possible your system uses a cmos battery and it is dead. It's separate from the main battery and handles date/time/bios.
Just look for something that looks like a button battery inside your laptop. Sometimes it's wrapped in plastic. My old Dell had it wrapped in rubber which held the wires in place and had a special connector.
Newer systems don't have them - they just rely on the main battery. But if yours is losing time/settings you might have one with a separate battery. It's usually a cr2032 or similar.
Does the european version work in the US with their slightly different frequencies? Personally, I'm a little leery of the entire Murena thing. I get the privacy angle, but I'm more interested in the hardware.