Hi, I bought a new battery for my n810 but it doesn't work. The battery says BP-4L (for E71/N97). Even it doesn't mention n810, I thought if it is BP-4L it should work in n810 then bought it. It fits n810 well, and when powered on, the screen showed NOKIA then turned off (tried many times, it's the same). I charged the battery using an external charger. I suspect that the battery may be ok, but there seems be an internal circuit to check the battery. Since this battery is not a geniue nokia one, the OS may block it. I am just wondering if my guess is right? Or it might be something else. Thanks. BTW, the n810 works fine with the stocked battery.