[Q]Prototype phone?

Soo. My mum got a new phone and gave me her old Xperia S because i had a old nokia. So I open it up to change the sim and I notice that it says it's a prototype so i was wondering if I could update it because it is stuck on a really old android and im to scared to use a rom to update.

PS.it wont work with OTA

PPS. It might be a ericsson because it has the logo on the back

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