My girlfriend has a sk17i (mini pro, stock jellybean) and I an E15i (X8, flashed with GingerDX, last version). Both uses EP500 battery.
The problem is that since last wednesday, her phone just keep rebooting, always after bootanimation, when lock screen appears. After some investigation, I discovered that it occurs only when the SIM card in inserted. Without it, the phone works ok! I've tried this battery in my X8 and is the same, with SIM card the phone keeps rebooting, without, works ok.
If I use the battery from my x8, both phones works great.
Any suggestion? I've tried to wipe battery stats through my phone, nothing changed..
PS: I asked here in X8, because I've use a lot this forum!! Prefer here than sk17i one