v2.2.5 150421 ds-7608ni-se/p

Hello all, Looking to upgrade an old Hikvision NVR DS-7608NI-SE/P. I've been reading through the forums and one thing that worries me is doing firmware upgrade from 2.x.x to 3.x.x My serial indicates "P0820151208BBRR" region is "other". Details: Firmware version is: V2.2.5 build 150421...